w. w. O. Beveridge and H. B. Fa'Wc'Us 315

walks and drives, it has a splendid future before it,and that at no, distant date.

On my way back to Lisbon I was fortunate enough to see the whole of the royal procession (with all the gala, state coaches, &c.), which was escorting the French President from Belem to Lisbon. In the evening, I spent nearly four hours in seeing the grand public illuminations, which were on a lavish scale, and by far the prettiest. and most elaborate of any that I have ever seen-and I have been in many capitals and large towns on special gala days.

When at last I had to bid good-bye to Portugal, I did so with decided regret, for I had passed a very pleasant time there, and I can confidently recommend it to anyone wishing for a delightful holiday in a country not yet overrun by tourists. Travelling is not expensive, and English and French are spoken in all the more important hotels and shops. The currency may possibly be somewhat puzzling to strangers at first, but not more so than if they were travelling in North America. The milreis is practically the same as the American gold dollar (4s. 2d.), but contains 1,000 reis instead of 100 cents, therefore 10 reis are equal to 1 cent or half­penny; so that an a:rticle priced at 750 reis is worth 75 halfpence, or 37i pence, or 3s. ltd. For practical purposes, 5 milreis may be

. roughly taken as the equivalent of one guinea .

• lReport.

FROM THE HYGIENiC LABORATORIES OF THE ROYAL ARMY MEDICAL

COLLEGE.

EXPERIMENTS WITH PRESERVED MEAT.! By MAJOR W. W. O. BEVERIDGE, D.S.O., AND CAPTAIN H. B. FAWCUS.

Royal Army Medical Corp8.

A.-EXPERIMENTS AS TO THE PENETRATION OF HEAT INTO THE

SUBSTANCE OF THE MEAT IN TINS DURING STERILISATION.

IN order to ascertain, with any certainty, the temperature in the centre of the meat during sterilisation, it was found necessary to devise a special form of thermometer which would record accurately the varia­tions of heat within the meat while the tin was hermetically sealed. We found that the usual method of inserting a thermometer through an open

J Being a Report to the Sub-Committee on Food of the War Office Committee on the Phsyiological Effects of Food, Training, and Clothing on the Soldier.

22

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316 Ewperiments ~vith Preset'ved Meat

Q

- ~ -----------~

DIAGRAM OF THE SPECIAL THERMOMETER in situ,

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w. W. 0.' Beveridge and H. B. FawGUs 317

hole in the tin, would not simulate the conditions under which heat penetrated when a vacuum was present and the tin hermetically sealed, these being the conditions under which the tins are sterilised by the manufacturers: The following is a description of the special thermo­meter used, which we found to be in .all respects satisfactory.

The thermometer A (see diagram) has a scale marked from 1000 to 1200 C., and is self-registering. This scale was chosen ~ecause the variations of temperature necessary for the experiments were included within it, and it was necessary to keep the thermometer, within a con­venient length. To ensure an air-tight joint the thermometer is made to pass through a brass shoulder C, and is kept in position by means of rubber and brass washers, which are tightened to any degree by means of the screw cap B. To use the thermometer, a hole is first drilled in the centre of one end of the tin of meat, and the brass shoulder is soldered securely on to the tin, covering the hole. The thermometer is then passed down into the meat, until its bulb lies exactly in the centre. The washers are passed over the thermometer and pressed down into the shoulder by means of the screw cap, which is then tightened, thus expanding the rubber washer and ensuring an absolutely air-tight union. In this way it is easy to record correctly the moment at which the centre of the meat reaches any temperature between 1000 and 1200 C., under precisely similar condition;; to those which bold when the tins are sterilised commercially.

A series of experiments was carried out to show the rate of pene­tration of heat, using the above tbermometer. The tins of meat used were selected from the new American supply. It is evident that for steri­lisation the centre of the meat in, the tin must reach at least 1000 C,' therefore temperatures below this point were not recorded. When a tin is simply boiled in water, we found by experiment that the temperature in the centre of the meat did not reach 1000 C. in five hours. In order to obtain temperatures higher than this, we used a solution of calcium chloride, the boiling points of wbich varied as required between 1070 C. and 1300 C.

Experiment I.-To find the length of time necessary for the tempera­ture in the centre of the meat to reach 1000 C., or higher, when the hermetically stlaled tin is immersed in fluid boiling at 1070 C.

(a) A l-lb tin of corned beef was placed in the boiling fluid. rrbe thermometer in the centre of the meat registered as follows ;-

100° C. in 1 hour 18 minutes 102 " ,,1 ,,30 "

After removal from the boiling fluid the temperature reached 1040 C.

(b) A 2-lb tin placed in fluid boiling at 1070 C. under the. same con­ditions. The thermometer in the centre of the meat registered ;-

1000 C. in 1 hour 22 minutes 102 " ,,1 ,,29 "

After removal from the boiling fluid the temperature reached 1040 C.

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318 Ewperirnents with PTeseTved Meat

(c) A I-lb. tin in fluid boiling at 1070 C. Thermometer III oentra registered :-

100° C.

102 " 105 "

106 " 107 "

in 1 hour 10 minutes

,,1 " 16 ,,1 " 38

,,2 " ,,2 " 15

(d) A 2-lb. tin in fluid boiling at 1070 C. Thermometer in oentre regIstered :-

100° O.

101" 102 ••

in 1 honr 16 minutes

., 1 ,,21 " "1,, 23

103 " ,,1 " 33 42 58

104 " ,,1 " 105 " q 1 106 " was not reached in three hours.

(e) A 2-lb. tin in fluid boiling at 1070 O. Thermometer m centre registered :-

100° C. in 2 hours 54 minutes 101 " ,,2 " 59 102 " ,,3 " 41

Note.-The meat in this tin was very closely packed.

(f) A 2-111. tin in fluid boiling at 1070 O. Thermometer in centre registered :-

1000 O. 101 ,.

102 " 103 "

104 "

in 1 hour 36 minutes " 1 45 ,,1 " 51 ,,1 " 57 ,,2 " 5 "

" Note.-It did not reach 105° in 2~ hours. All these tins were markedly blown when

removed from the fluid.

Experiment II.- The same samples, after removal from' the fluid boiling at 1070 0., were punctured to allow escape of steam, and imme­diately re-sealed, so as to cause as much of a vacuum as possible. They were then immersed in a fluid boiling at 1200 O.

(a) A I-lb. tin in fluid boiling at 1200 C. Thermometer in oentre registered :-

1000 C.

. 102 " , 105 "

110 " 115 ,.

in 34 minutes

,,38 " ,,44 " ,', 54 " ., 1 hou~ 8 minutes

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(h) A 2-lb. tin in fluid boiling at 1200 C. Thermometer ID centre registered :-

]00° C. 105 ;. 110 " 115 "

in 34 minutes

" 47 " ,,55 " " 1 hour 10 minutes

(c) A I-lb. tin in fluid boiling at 120° C. Thermometer in centre registered :-

100° C. 18 minutes

105 " 24 " 110 " ,,30 " 115 " ,,42 "

Note.-This tin had a small hole in the solder, and steam escaped during heating.

(d) A 2-1b. tin in fluid boiling at 1200 C. Thermometer in centre registered :- .

lOO" C. in 13 minutes

103 " 104 " 105 "

,,14 " " 14rr " ,,15 "

(e) A 2-lb. tin registered: -

in fluid boiling at 1200 C. Thermometer ID centre

1000 C. in 57 minutes 105 " " 1 hour 7 minutes 110 " " 1 " 22 115 " " 1 " 35

Note.-The meat in this tin was very tightly packed.

(f) A 2-lb. tin in fluid boiling at 1200 C. Thermometer in centre registered :-

1000 C. 105" 110 " 115"

in 24 minutes

25 I'

" 27~ " " 36

Experiment III.-A I-lb. tin in fluid boiling at 1150 C. Thermometer in centre registered :-

100° C.

105 " 110 " 113 "

in 39 minutes

" 45 " 54 " 75

Experiment IV.-(a) A 2-1b. tin in fluid boiling at 1300 C. The thermo-meter in centre registered :-

100° C. in 13 minutes

105 " " 18 110 " ,,23 "

The temperature did not rise above 110' C. in 2 hours 20 minutes.

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320 Ewperiments 1'vith Prese1"ved Meat

(b) A 2olb. tin in fluid boiling at 1300 O. The thermometer in centre registered :- '

1000 C. in 22 minutes 105 " 110 " 115 " 117 "

" 26 " 32 " 39 " 52

Similar experiments were carried o~t, with other tins, the results of which are recorded in the following table :-

TABLE I.

Tempera- RATE OF PENETRATION IN MINUTES

Size of tin ture of bath "I 1

1000 1010 1020 I, 1030 1040 I 1000 110' 115°, llto

----------- ---,---------'---------llb. 1070 O.

" " " " " ., '

" " Average minutes

39 42 46 I 49 52 60 _ _ . _ .. 40 44 47 I 52 58 62 .. _ _ .. 66 73 81, 89 94 100 .. .. .. 70 76 I" .. 98 .. .. .. 78 90.. .. .. ..

58'6 .. (;8-1-··- - .. -180-- - .. - --.. - --.. -lIb. 1200 C.

" " " " " " " "

Average minutes

17 -.-. - --.-. -1-'-' ---"-1-2229 Ss -.-. -18 " " .. .. 22 32 35 •• 18 . . I • • • • • • 24 30 42 I •• 24 . . . . , . . . . 1 25 27 36 .. 34 . . . . I • • • • 44 54 68 ..

I ,

22-2.. .. 1-.. _--"J~27~ 3<!'5 43~ ..

21bs. 1070 C. 76 81 83 93 102 108 .. .. .. ,.

" 94 98 103 108 114 125 .. .. ..

1

" " " " " "

98 109 118 123 128 131 .. .. .. 99 103 106 109 115 118 .. .. ..

108 115 121 125 129 133 . . . . . .

Average minutes

21bs. 1200 C.

" " " " " " " "

95101:; 106:;1111:(3 m:5Tl23- . . ----15 - .. -'1--.. ---.. -1-20 27 39 15 ...... ; 21 29 44 19 ...... I 26 35 47 34 .. I.. .. i 47 55 70 57 . . . . . . . . ! 67 82 95 ..

------,------,-----------Average minutes

2 Ibs. 1300 C.

28 .. .. I.. . . I 36'2 45'6 59 ..

13 - .. - --"-!-"-I-.. -[18- 23 22 . . . . i • • • • I 26 22 39 52

It will be seen on reference to the above table that when tins of meat of identical size and shape are immersed in fluid boiling at a certain temperature, there is considerable variation in the length of time reqnired for the centre of the meat to reach a given temperature. The cause of this is somewhat uncertain. Each experiment was carried ont in an identical manner, so that the cause mnst have been in the tins theme

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w. w. O. Beveridge and H. B. Fawcu8 321

selves. It is probable that the rate of penetration of the heatis influenced by the amount of fat present in the meat. The percentage amount of this is found to vary considerably in different tins. The fact of the meat being tightly or loosely packed, and the condition of the vacuum present, may also favour or retard the penetration of the heat.

B.-BACTERIOLOGICAL INVESTIGATION TO DETERMINE THE THERMAL DEATH POINT, AND THE OPTIMUM TEMPERATURE OF GROWTH OF THE ORGANISM ISOLATED, BY MAJOR C. E. P. FOWLER, R.A.M.C.

The organism isolated by Major Fowler from blown tins of corned meat, referred to in a previous report to the Committee, is apparently identical with the Bacillus cadaveris sporogenes of Klein, and the B. plttrificus coli of Bienstock. Upon further investigation it is found to have the following characters, which include those already given by Major Fowler :-

Morphology.--A bacillus which varies greatly in length, the average size being about 6 p. long by 0'6 p. broad. Ends rounded. Motile, with slow waving movement. Is usually seen with a large terminal oval spore. Stains with all the ordinary dyes, and retains the stain by Gram's method.

Growth.-It is a strict anaerobe. Somotimes it presents the appear­ance of growing aerobically in milk cultures. This is due to the scum forming on the surface of the milk, which converts it into an anaerobic culture. It grows slowly at all temperatures. The optimum temperature of growth is 37° O. It grows well at 42° 0., but its growth at room tem­perature is extremely slow. Milk cultures kept at 17-22° O. rarely become decomposed in a month. Tubes of milk inoculated with the B. cadaveris were incubated at temperatures of 42° C., 37°' C., and 22° O. The milk at the two higher temperatures became decomposed within seven days. 'J'hat at 22° C. remained unchanged at the end of thirty-four days. At the end of that time it W3,S transferred to a 37° C. incubator, when it became completely decomposed within four days. In all cultures it gives off an exceedingly putrid odour.

Agar Slope.-After three or four days at 37° C., there is a yellowish­brown growth, generally of discrete circular colonies, with irregular edges, which appear granular under a low power. At first few spores are formed, but later many appear.

Broth.-After about four days at 37° 0., growth visible at the bottom of the tube as a fine granular deposit, the upper part of the medium being usually clear. Putrid odour.

Gelatin.-Slow softening after seven to nine days at 22° C. Colonies show filamentous offshoots. Later the gelatin becomes completely liquefied and the growth sinks' to the bottom, leaving the upper part of the medium clear. '

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322 Ewperiments with Preserved M'eat

Litmus Milk.-After four or five days at 37° C. the milk is decolorised and sometimes clotted. Later slow digestion of the casein takes place, leaving a clear yellow whey. No gas is formed. When the culture is exposed to the air and shaken, the upper layers of the medium become bluish-red. The milk is completely digested in from seven to fourteen days, leaving merely a granular deposit at the bottom of the tube.

Neutral Red Glucose-agar.-After about three days at 37° C. there is free gas formation, and the red colour becomes reduced to a bright yellow.

One per cent. Glucose-peptone.-Strong growth; moderate amount of gas is formed, and slight acidity; few spores.

One per cent. Lactose-peptone.-Feeble growth; no gas; no acid; few spores.

One per cent. Sucrose-peptone.-Feeble growth; very slight formation of-gas and acidity; few spores.

One per cent. Mannite-peptone.-Growth, but no gas or acid; few :spores.

Nitrate Broth, one per cent.-No reduction to nitrites. 111acOonkey's Bile Salt Broth.-Growth; a~id but no gas. Peptone and Salt.-Indol negative. Effect on Animals.-The organism was found by Major Fowler to be

non-pathogenic to guinea-pigs when injected hypodermic ally and intra­peritoneally. Feeding experiments have, however, not yet been carried out.

Ohemical Action.-Tissier and Martelly (Annal.Inst. Pasteur, Sep­tember 25th, 1902) found that the action of the bacillus was paralysed by a 1'75 per cent. acidity, reckoned as H 2 S04 • It was found that different strains of the organism varied considerably in their activity in the various media. The organism shows the greatest 'activity in the presence of pure proteid matter, which it attacks with avidity, forming abundance of gas, with an exceedingly putrid odour. On analysis this gas was found to consist of over 50 per cent. of carbon dioxide, together with considerable quantities of hydrogen sulphide and some hydrogen. Methane and methyl mercaptan were also present. The exceedingly putrid odour of the gas is evidently due to the presence of hydrogen sulphide and methyl mercaptan. '

All the tins of decomposed meat examined showed a decided increase of the acidity over that normally present in sound tins. This is un­doubtedly due to the action of this bacillus. As before mentioned, its action is paralysed by acidity amounting to 1'75 per cent. This would explain the phenomenon, which is sometimes found, of a blown tin of meat being apparently sterile on examination.

Occurrence.-The bacillus is said to be a normal but not numerous inhabitant of the intestine of men and animals. Tissier and Martelly (loc. cit.) found this bacillus among others in every sample of fresh meat

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w W O. Beveridge and H. B. Fawc'u.'! 323

which they obtained from the butcheries of Paris, so that the contamina­tion of tinned meat would appear to take place in the slaughter-house, and during the manipulation necessary to the process of canning.

It is probable that this bacillus is of more wide-spread occurrence ,than is usually supposed, as we have evidence that it is present in many samples of milk. For instance, two samples of fresh milk received from a neighbouring dairy, on prolonged incubation at 37° C., after boiling to destroy non-spore-bearing bacteria', became decomposed, and on examina­tion this bacillus was found.

Thermal Death Point.

To ascertain this, the fOllowing experiments were carried out;-

Series 1. (1) Milk cultures of this bacillus were sealed in small glass capsules,

containing about 0'2 cc. These were then suspended in a wire cage in a solution kept boiling at 100° C.

No. 1 capsule in the fluid at 100° C. for .. 2 3 4

"" "

5 minutes .. 10 .. 15 .. 20

" 5-Control capsule at laboratory temperature.

Each capsule, on being taken out of the fluid, was dropped into cold water. It was then opened, the contents inoculated into tubes of neutral red glucose-agar and litmus milk, and incubated anaerobically at 37° C. At the end of forty-eight hours all neutral red agar tubes, and at the end of four days all milk tubes, gave a typical reaction. The B. cadaveris was recovered from all the milk tubes. Therefore B. cadiweris spores can survive a temperature of 1000 C. for twenty minutes.

(2) Four tubes of neutral red glucose-agar were inoculated with an agar culture of B. cadaveris (bacilli and spores), and then placed in a solution boiling at 100° C.

No. 1 tube for

" 2 " 3 " 4

10 minutes 20 30 40

" On being removed from the fluid each tube was cooled rapidly under

the tap, and incubated anaerobically at 37° C. At the end of forty-eight hours all tubes gave a typical reaction and the bacillus was recovered. Therefore B. cadaveris spores can survive a temperatu1'e of 100° C. for forty minutes.

For further experiments in the thermal death-point, an emulsion of B. cadaveris was made thus;-

A 4 per cent. emulsion of dried human falces in water was made and sterilised. To 100 cc. of this, several milk cultures of B. cadaveris were

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324 Experiments with Presm·rved Meat

added, thus making a rich emulsion of the organism in a fluid containing natural organic matter, simulating more or less the conditions in which it occurs in nature. This is referred to in future as the "cadaveris­fffices " emulsion.

(3) Four glass capsules fluid boiling at 1000 c.

No. 1 capsule for .. 2

" 3 " ,4

of cadaveris-fffices emulsion were placed in

30 minutes 45 60 75

The capsules were cooled as before, and the contents inoculated into litmm; milk and neutral red glucose-agar tubes. Typical reactions were obtained in all tubes within seven days, and the bacillus was recovered. Therefore B. cadaveris spores can survive 1000 o. for one and a quarter hours.

(4) An emulsion from an agar slope of B. cadaveris was sealed in a small glass capsule, and suspended in a solution, boiling at 110° 0., for two minutes. The capsule was cooled and contents inoculated as before. A typical reaction occurred, and the bacillus was recovered from the tubes. Therefore B. cadaveris spores can surv~ve a temperatnre of 1100

o. for two minntes. (5) An emulsion from an agar slope was sealed in a small glass

capsule, and suspended in a solution, boiling at nos 0., for three minutes. After cooling the contents were inoculated into neutral red agar and litmus milk tubes as before. A typical reaction was obtained in both tubes and the bacillus was recovered. Therefore B. cadaveris spores can survive a temperature of 1100 O. faT th1'ee minutes,

(6) Four glass capsules of cadaveris-fffices emulsion were placed in fluid boiling at 1100 o.

No. 1 capsule for

" 2 " 3

3 minutes 5 7

Capsules cooled and contents inoculated as before. ,A typical reaction was obtained in the cultures and the bacillus was recovered. Therefore B. cadaveris spores can survive a temperature of 1100 o. for seven minutes.

(7) Five capsules of cadaveris-fffices emulsion were immersed in fluid boiling at 110Q c.

No. 1 capsule for 2

3

" 4 5

5 minutes 10 15 20 30

Capsules cooled and contents sown into neutral red agar, litmus milk and broth, All tubes gave a typical reaction and the bacillus was

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w. W. O. Beveridge and H.B. Fawcu8 325

recovered. Therefore B. cadaveris spores can survive a temperature of noo O. for thirty minutes.

(8) Three small glass capsules of cadaveris-freces emulsion were immersed in fluid boiling at 110° C.

No. 1 capsule for .. 30 minutes

" 2 45 " 3 60

The capsules were then cooled and con"tents inoculated as before. Cul­tures from all three capsules showed typical reactions and the bacillus was recovered. Therefore B. cadaveris spores can survive a temperature of 110° O. for sixty minutes.

(9) Six capsules of cadaveris-freces emulsion, as above, were immersed in fluid boiling at 112° C.

, No. 1 capsule for 2

" 3 4 5

" 6

5 minutes 10 15 20 25 30

The capsules were then cooled and contents sown as before. Cultures from capsules Nos. 1, 2, 3, and 4 gave typical reactions, and the bacillus was recovered from them. Cultures from 5 and 6 remained sterile. Therefore the B. cadaveris spores can survive a temperature of 112° O. for twenty minutes, bltt are killed by the same temperature in twenty-five minutes.

'(10) Three capsules of cadaveris-freces emulsion, as above, were immersed in fluid boiling at 115° C.

No. 1 capsule for

" 2 " 3

5 minutes 10 15

Cultures from No. 1 gave typical reactions. Cultures from Nos. 2 and 3 remained sterile. Therefore B. cadaveris spores can survive a tempera­tt~re of 115° O. for five minutes, but are killed by the same temperature in ten minIttes.

(11) Capsules of cadaveris-freces emulsion, as above, were immersed "in fluid boiling at 117° C.

No. 1 capsule for .. 5 minutes

" 2 10

The capsules were cooled and contents sown as before. All the cultures from these capsules remained sterile. Therefore B. cadaveris spores are killed by a temperature of 117° O. in five minutes.

From these eleven experiments it would appear that the spores of this bacillus are only killed by a temperature of 112° C. in twenty·five minutes, 115° C. in ten minutes, or 117° C. in less than five minutes. The results of the foregoing experiments are, embodied in the following table :-

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326 Emperiments with Presm'ved Meat

TABLE n. EXPERIMENTS WITH GLASS, OAPSULES OF OADAVERIS-FlECES EMULSION, SHOWING

MINUTES REQUIRED TO KILL B. cadaveris SPORES WHEN EXPOSED TO CERTAIN

TEMPERATURES.

TEMPERA-TURE

1000 C. 110

112 " 115 " 117

5~- 15

+ + + + + + + + + +

+ Spores survived.

20

+ + +

MINUTES

25 30 45 ~75

+ + + + + + + + +

- Spores killed.

Series II.-Experiments with Tins of Oompressed Meat Inoculated with the Sp01"eS of B. cadaveris.

Experiment L--A I-lb. tin (jiin " A ") of corned beef was inoculated with an agar emulsion of B. cadaveris (one-month-old culture) thus: A hole was bored in the tin and about 0'0 cc. of the cadaveris-frnces emulsion was injected into the centre of the meat with a sterile pipette. The hole was then soldered up, and the tin placed in a fluid boiling at 100° C. for thirty minutes. It was then cooled and incubated at 37° C. for sixteen days. At the end of this time the tin was not blown, and on puncturing there was no escape of gas. Gas had not escaped, ,as the sides and top remained concave. On opening the tin the meat was not discoloured or decomposed, but some of the frnces appeared to be somewhat digested. There was no apparent bad smell. The acidity mounted to 0'81 per cent. as lactic acid. Some of the contents, both meat and liquid, were sown into litmus milk, neutral red agar and broth tubes. All tubes gave a typical reaction, and the bacillus was recovered in three days.

Result.-B. cadaveris recovered from a tin of meat after exposure to a temperature of 100° C. for thirty minutes.

Note.-As already shown in the first part of this report, the tempera­ture in the centre of the meat had not reached 100° C.

Experiment n.-A I-lb. tin of corned beef (tin" B ") was inoculated in the same way as in the above experiment and re-sealed.' The tin was then placed in fluid boiling at 107° to 108° C. for thirty minutes. It was then punctured to relieve pressure, and re-soldered, cooled, and incubated at 37° C. At the end of fifteen days the tin was very much distended with gas. On opening there was a strong rush of gas with a very putrid odour. A good deal of turbid fluid escaped. The meat was not dis­coloured, but was softened, and the fibres separated by gas. The acidity was 0'81 per cent. as lactic acid. Cultures were made from both the juice and the meat and a typical reaction obtained, and the bacillus was recovered from all the tubes.

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w. W. O. Beveridge and H. B. Fawcus 327

Result.-The B. cadaveris was recovered alive from a tin of meat which had been exposed to a temperature of 1070 C. for thirty minutes.

Note.-On reference to the first part of this report it will be noticed that the temperature in the centre of the meat did not reach 1000 C. in this period of time.

Experiment III.-A small tin of about 2-ounce capacity (tin "0") was tightly packed with corned beef and inoculated with cadaveris-freces emulsion. The special thermometer was sealed into it. It was then immersed in fluid boiling at 1100 C. The thermometer registered :-

100° C. iu 15~ miuutes 105 " " 18i1; 110 " .. 25

The tin was taken out after fifty minutes. It was then cooled, opened, and the whole of its contents were placed in two large sterile test tubes and incubated anaerobically at 370 C. After six days there was commencing gas formation with putrid smell. Cultures made from the meat showed typical reactions and the bacillus was recovered.

Result.-B. cadaveris spores can survive a temperature of 1100 C. for twenty-five minutes.

Experiments IV. and V.-Two I-lb. tins of corned beef (tins" D " and" E ") were inoculated in the same manner as above with about 1 cc. of cadaveris-freces emulsion. In one tin (E) the special thermometer was sealed with the bulb in the centre of the meat. Both tins were then immersed in fluid boiling at 1150 O. It was assumed in this experiment .that the temperature in tin D would be the same as that registered by the thermometer in tin E. The thermometer in tin E registered :-

lOO? C. in 39 minutes

105 " 45 110 " 54 112 " 63 113 " " 75

The tin without the thermometer (D) was reJ;lloved from the fluid after sixty minutes, the temperature in the tin E being 111'50 O. It was punctured to relieve pressure and immediately re-sealed. It was then placed in cold water for one hour, when the sides of the tin becamedis­tinctly concave. The tin was then incubated at 370 C. In seven days the tin was much distended by gas. On opening it there was a rush of evil-smelling gas. Oultures made from both the meat and the juice gave typical reactions. A loopful taken from the juice showed on examination numerous bacilli and spores.

Result.-B. cadaveris was recovered from a tin which had been ex­posed to a temperature of 1150 O. for one hour.

Note.-From comparison with the tin E the centre of the meat bad probably been exposed to a temperature of 1000 C. and over for twenty~ one minutes, 1100 C. and over for six minutes, and 111'50 O. momentarily.

Tin E.-The tin which contained the thermometer CB) was removed

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328 E[Cperimenis with Pre.served Meat

from the fluid after seventy-five minutes, the temperature in the centre of the meat being 113° C. This tin was treated in exactly the same manner as tin D. At the end of thirteen days this tin showed no signs of blowing. When punctured under water, the water was sucked in, showing that a vacuum still remained. On opening the tin there was no smell and the meat appeared to be sound. Cultures were made both from the meat and juice, and portions of the meat were also incubated anaerobically in broth. No reaction was obtained in any of the tubes, and the meat appeared to be sterile. The acidity in this case was only 0'45 per cent. as lactic acid, which is the normal percentage of acidity found in sound tinned meats.

Result.-B. cada~eris was not recovered from a tin of corned meat after exposure to a temperature of 115° C. for seventy-five minutes.

Note.-The supposition is that the spores of this bacillus had been killed, by a temperature of 1120 O. to 113Q O. for twelve minutes, as we know that temperatures below this do not kill them.

Experiments VI. and VII.-Two I-lb. tins of corned beef (tins" F" and" G ") were inoculated with about 1 cc. of cadaveris-fffices emulsion. Into tin G the special thermometer was sealed, with the bulb in the centre of the meat. Both tins were then immersed in fluid boiling at 1200 O. The thermometer in tin" G" registered:-

1000 C. in 24 minutes 105 " " 25 110 " " 272-

115 " " 36 Tin F was removed from the fluid after thirty-one minutes, the

temperature in tin G being 112.5° C. After being punctured, re-sealed and cooled, it was incubated at 37° O. After thirteen days the tin showed· no signs of blowing. On being punctured under water, the water was sucked in. On opening, the meat appeared sound and had no bad smell. Acidity, 0'72 per cent. as lactic acid. Cultures made from the juice and meat showed typical reactions, and the bacillus was recovered from all the tubes.

Result.-B. cadaveris was recovered from a tin which had been exposed to a temperature of 1200 O. for thirty-one minutes.

Note.-From comparison with tin G the centre of the meat had prob­ably been exposed to a temperature of 112.5° O. momentarily.

Tin G.-Tin G was removed from the fluid after thirty-six minutes, the temperature in the meat, as registered by the thermometer, being 115° C. It was treated in exactly the same manner as tin E. After fourteen days' incubation the tin was slightly blown, and some gas escaped on puncture under water. The meat was not decomposed. Cultures made from the meat and juice all showed typical reactions, and the bacillus was recovered from all the tubes.

Result.-B. cadaveris was recovered from a tin of corned meat which had been exposed to a temperatur e of 1200 C. for thirty-six ininutes.

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w W. O. Bevel'idge and H. B. Fawcus 329

Note.-The centre of the meat, as shown by the thermometer, had been exposed to a temperature of 112° C. and over for five minutes, and 115° C. momentarily.

These seven experiments with inoculated tins would tend to show that the spores of this bacillus can survive a temperature of 112° C. for five minutes, but are killed by a temperature of 112° C. for twelve minutes. On the contrary, the eleven experiments with glass capsules described above show that the spores can survive a temperature of 112° C. for twenty minutes, but are killed by the same temperature in twenty-five minutes. These latter experiments show that the actual thermal death point of the spores is a tempera,ture of 112° C. acting for from twenty to twenty-five minutes, or 115° C. acting for from five to ten minutes. The discrepancy in the length of time apparently required to kill the spores in the experiments with tins of meat and those with glass capsules can be explained by the f~ct that the temperature in the centre of a tin of meat would remain at 112° C., or over, for some time after the tin was removed from the fluid. This is not the case with the glass capsules, therefore the results obtained by using them are more likely to be accurate. It is also probable that the spores are killed immediately by a temperature of 117° C.

GENERAL CONCLUSIONS.

(a) The bacillus under consideration, although non-pathogenic to animals, decomposes tinned meats and renders them quite unfit for eon­sumption. Therefore processes of sterilisation of tins of meat mus" be used which will destroy the spores of this bacillus. The optimum tem­perature of growth of this bacillus is blood heat (37° C.). At this tem­perature inoculated tins of meat become rapidly decomposed, but this decomposition is not necessarily made apparent at once by the presence of gas in the tin. Blowing of the tins often does not take place within a fortnight, even at this temperature. Tins of meat contaminated with the spores of this bacillus could be kept at temperatures of 22° C. and under for many months, without showing any signs of blowing. If, however, such contaminated tins, although apparently sound when examined in this country, were exposed to a temperature such as is likely to be met with in thE:) Tropics, they would rapidly become decom posed.

(b) The rate of penetration of heat into the substance of the meat in tins during sterilisation is extremely variable. We have based our conclusions on the average of many experiments. To ensure complete sterilisation, the temperature of the medium surrounding the tins must always be above 112° C. The lowest temperature of the surrounding fluid which will completely sterilise the tins within a reasonable time is 120° C., and this temperature must act for not less than sixty minutes. From the two experiments recorded with a fluid boiling at 130° C., it

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330

would appear that even then ab least an hour would be required to ensure the death of these very resistant spores. We are aware that the above results do not tally with the l}sually accepted idea of the thermal death point of spore-bearing bacilli, but we would point out that experiments have not before, to our knowledge, been made with this particular bacillus. The experiments were carried out with every available precau­tion against error, and repeated often enough to ensure accuracy .

•

lRe\)iewa.

THE THEORY AND PRACTICE OF HYGIENE (Notter and Firth), revised and largely rewritten by Lieutenant-Oolonel R. H. Firth, R.A.M.O. Third Edition. London: J. and A. Ohurchill, 1908. 993 pp. quarto. Price 21s. net.

The appear:ance of the third edition of this standard and monumental work will be hailed with satisfaction on all sides. Colonel Firth has spared no pains to bring his book thoroughly up t~ date, and in fact, the letterpress is very largely quite new. The chapters most extensively modified are those dealing with water, food, habitations, removal and disposal of sewage, disposal of the dead, offensive trades, parasites, infectious diseases, disinfection, vital statistics, and last, but not least, military hygiene. The last chapter runs to sixty-two pages, and con­tains much new and interesting information, among which we note a full description, with a photograph, of the new Slack and Brownlow watercart that gave some of us so much trouble on manreuvres last summer.

As the subject of public health is now of such vital importance in the Army, we strongly recommend every officer of the Royal Army Medical Oorps to procure a copy of Oolonel Firth's book.

A. 1. F.

'rHE BACTERIOLOGICAL EXAMINATION OF DISINFECTANTS. By William Partridge, F.I.O. London: Sanitary Publishing Co., 1907. 2s. 6d. net.

This is a little book of some seventy pages, giving a clear and intel­ligible description of the methods of conducting an examination of a disinfectant by bacteriological testing. The requisites of a true dis­infectant are set forbh; the fallacy of chemical methods of testing, as a praCtical guide to disinfectant value, is explained; and an account of the bacteriological procedure, according 'to the Rideal-Walker method, is given in detail, with illustrations of the apparatus required. The last two chapters describe the modifications that have been suggested in this method, viz., the use of sterile urine by Klein; of milk by Meredith, Wynter Blyth; of gelatin, mucin, &c., by Sommerville and Walker; and the two other processes, similar in principle, but different in technical details of procedure, viz., the "garnet" method and the "thread"

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