SECTION VI.— CALCIUM OXIDE.
Recently slacked lime and lime-wash have long enjoyed a reputation as disinfectants, and have been extensively used by sanitarians in their efforts to restrict the extension of infectious diseases. But until recently 110 exact experiments have been made to determine the precise germicide value of caustic lime. Koch, in 1S81, found that lime-water only had a slight restraining influence upon the development of anthrax spores which had been immersed in it for 15 to 20 days. My own experiments upon spores have given results in accord with this. But, inasmuch as we have only in exceptional cases to deal with spores, in our practical measures of disinfection it is well worth while to carry the investigation further, and inquire what value this agent may have for the destruction of pathogenic organisms which do not produce spores. This has recent- ly been done by Dr. Paul Liborius, a medical officer of the Russian navy, whose researches have been made in the Hygieniscken Institut of Berlin.1
In a first series of experiments putrid bouillon was mixed with lime water in the proportion of 2 : 1, 1:1,3:5, and 1 : 5. These mixtures were allowed to stand for three weeks, and tests were made at intervals to ascertain whether the micro-organisms present were still capable of development. The result is stated by Liborius as follows :
"Of the various micro-organisms in the putrid bouillon, by far the greater part were destroyed within twenty-four hours, when the propor- tion of lime at the commencement of the experiment was about 0.09 per cent. The few germs which resisted were restricted in their develop- ment, and only multiplied again after a considerable time, when proba- bly the amount of lime in solution was to a considerable extent dimin- ished."
As the result of extended experiments upon the bacillus of typhoid fever and the spirillum of Asiatic cholera, Liborius arrives at the follow- ing conclusions :
An aqueous solution of calcium oxide of the strength of 0.0074 per cent, in the course of a few hours destroys the typhoid bacillus, and a solution of 0.0246 per cent! destroys cholera bacilli.
Bouillon cultures of the cholera bacillus, containing albuminous precipitate (unfiltered bouillon), which offer at least as unfavorable con-
1 Einige Untersuchungen Uher die desinficirende Wirkung des Kalkes, Zeitschrift fur Hygiene, 131 II. 18S7.
170
REPORT OF COMMITTEE ON DISINFECTANTS.
ditions, on account of their physical characters, as natural cholera dejec- tions, are perfectly disinfected in the course of a few hours by a 0.4 per cent. solution of pure caustic lime, = to 2 per cent, of crude burnt lime in fragments.
- The most energetic action of lime was obtained, under more diffi- cult circumstances, when it was used in the form of pure pulverized caustic lime, or as a milk of lime containing 20 per cent, of the same.
Liborius calculates that 12 grammes of pure caustic lime would suffice to disinfect the alvine discharges during 24 hours in a case of cholera. He says that pure calcium oxide costs from 50 to 70 pfennings per kilo- gram, or by the quantity from 40 to 50 marks per 100 kilograms (about $5 to $6 per 100 pounds).
" If, upon further researches, it is found necessary to add a certain proportion of magnesium chloride to prevent the development of ammo- nia, one tenth of the amount of lime will suffice. As the purest magne- sium chloride is no dearer than caustic lime, and as the price of crude burnt lime, at the factory, is only 1^ marks per hektolitre, the disinfec- tion of the daily dejections of a cholera patient would cost something less than one pfenning" (=about \ cent).
In order to test the conclusions reached by Liborius, I have made the following experiments with calcium oxide obtained from the chemical laboratory of the Johns Hopkins University, which is quite free from chlorine (manufactured by Dr. Theo. Schuchardt, ofGorlitz, Germany), I have not attempted to determine by chemical tests the exact amount ot calcium oxide present in my standard solution of lime water, but have prepared a saturated solution by adding the caustic lime in large excess to distilled water. According to the National Dispensatory, liquor calcis contains 0.15 per cent, of hydrate of calcium. The same authority states that calcium oxide is soluble in 750 parts of water at 15° C.
TABLE NO. XXXV.
CULTURES IN FLESH-PEPTONE GELATINE, MIXED WITH AN EQUAL QUANTITY OF LIME WATER. TEST IN ESMARCH's TUBES.
Organism.
Time of exposure.
Proportion of lime water.
Typhoid bacillus
50 per cent., 50 per cent., Cont.
Bacillus of Schweine-rothlauf .
50, 50, Cont.
Bacillus pyocyanus .
3
50, 50, Cont.
Bacillus acidi lactici
0 •a
50, 50, Cont.
Finkler-Prior spirillum
i
50, 50, Cont.
Cheese spirillum
50, 50, Cont.
Staphylococcus pyog. aureus .
50, 50, Cont.
Staphylococcus pyog. citreus .
50, 50, Cont.
REPORT OF COMMITTEE ON DISINFECTANTS. TABLE NO. XXXV— continued.
171
Organism.
Time of exposure.
Proportion of lime water.
Staphylococcus pyog. albus
«3
50,
50, Cont.
Typhoid bacillus
0
50,
50.
Bacillus pyocyanus .
X V
50,
50.
Bacillus acidi lactici .
a 0
J3
50,
50.
Finkler- Prior spirillum
50,
50.
Staphylococcus pyog. albus
|
50,
50.
Staphylococcus pyog. aureus .
O
50,
50.
TABLE NO. XXXVI.
CULTURES IN BOUILLON, MIXED WITH A SATURATED SOLUTION OP
CALCIUM OXIDE.
Organism.
Time of exposure.
Proportion of lime water.
Typhoid bacillus
it
1:1, 1 : 1, 5: 1. 5 : l.1
Staphylococcus pyog. albus
1:1, 1:1, 521, 5:1.
Typhoid bacillus
gS
1 : 1, 1 : 1.
Staphylococcus pyog. albus
1 : 1, 1 : 1.
TABLE NO. XXXVII. EXPERIMENTS WITH SPORES.
Spores of
Date.
Time of exposure.
Proportion
of
calcium oxide.
Result.
Anthrax bacillus.
April 19.
2 hours.
Saturated solution.
Not killed.
Wurtzel bacillus.
u
<(
H
-
Bacillus subtilis.
«i
M
"
<<
Bacillus alvei.
«<
<«
It
»
Anthrax bacillus.
April 20.
24 hours.
<«
M
Wurtzel bacillus.
M
«
<«
M
Bacillus subtilis.
N
(<
<«
M
Bacillus alvei.
<«
«
<«
M
1 Development retarded to fourth day.
172 REPORT OF COMMITTEE ON DISINFECTANTS.
TABLE NO. XXXVII— continued.
Spores of
Date.
Time of exposure.
Proportion
of
calcium oxide.
Result.
Anthrax bacillus.
April 21.
48 hours.
(«
Wurtzel bacillus.
"
u
"
Bacillus subtilis.
"
-
«<
Bacillus alvei.
M
<(
M
Anthrax bacillus. Wurtzel bacillus. Bacillus subtilis.
April 23. «
2 hours.
20 per cent, of pure calcium oxide suspended in a sat- urated solution of the same.
Bacillus alvei.
"■
"
TABLE NO. XXXVIII.
calcium oxide suspended in a saturated solution of the same
(lime-wash) .
Organism.
Date.
Proportion of calcium oxide by weight.
Typhoid bacillus
April 26, 1887.
1 : 40, 1 : 40.
April 27.
1 : 80, 1 : 80, 1 : 160, 1 : 160.
Staphylococcus pyog.
albus.
April 20.
1 : 40, 1 : 40, 1 : 80, 1 : 80,
1 : 160, 1 : 160.
The above experiments suffice to demonstrate the fact that pure cal- cium oxide has no great value for disinfecting purposes, and show that the proposition of Liborius to give it the preference over chloride of lime on account of its comparative cheapness is based upon a misconception of the practical value of the two agents for disinfecting purposes. Inas- much, however, as calcium oxide has considerable germicide power when used in the form of lime-wash, especially after prolonged contact, the general use of lime-wash for sanitary purposes is to be recommended wherever it can be applied to surfaces which are supposed to be infected by disease germs.
The following experiments have been made to determine the antisep- tic value of pure calcium oxide in a saturated aqueous solution :
In these experiments bouillon in the proportion indicated was added to lime water, in test tubes, and a drop of a culture containing the test organism was added to this mixture. The test tubes were then set aside, and the time noted when the bouillon became clouded by the multiplica- tion of the organisms with which it had been inoculated.
REPORT OF COMMITTEE ON DISINFECTANTS. 1 73
Mixtures were made in the proportion of 12 of bouillon to 1 of lime water 58:1,4:1, 2:1, and 1:1. Such mixtures inoculated with the cheese spirillum had all broken down in 24 hours. Inoculated with the typhoid bacillus, 12:1 became clouded in 24 hours, 8:1 in 48 hours, 4 : 1 in 72 hours, 2 : 1 in 5 days, 1:1 in 6 days. With staphylococcus pyogenes albus the result was the same. These experiments show that lime water mixed with an equal quantity of a culture solution exercises a consider- able restraining influence upon the development of the typhoid bacillus and upon the micrococcus tested, but that in the end these organisms are able to multiply in a culture solution to which it has been added in this proportion. It is somewhat remarkable that the cheese spirillum was not, apparently, restrained in its development by the same proportion of lime water. The writer's sudden departure for Brazil, to investigate the methods of inoculation against yellow fever practised in that country by Dr. Domingos Freire, has brought these experiments to a more speedy termination than he had intended.