1885.] 



Studies of Disinfectants by New Methods. 



271 



On the fourth day of cultivation the colonies produced were calcu- 

 lated to be equal to 33,846 per gram of the original sewage, which 

 when not disinfected yielded 1,490,000 per gram. It was noted that 

 the fungi were to the other organisms as 4 : 7. About 1500 of the 

 colonies were of the class that liquefy the gelatine. 



Quinine Sulphate. — A saturated solution of quinine sulphate was 

 made by boiling the crystals with water, allowing to cool, and filtering 

 from the crystals which separated. The strength of this solution was 

 ascertained by evaporating 10 c.c. to dryness in a tared platinum dish. 

 It was found in this way to be equal to 0'3 per cent, of the anhydrous 

 sulphate. 



1 gram of sewage was mixed with 50 grams of the saturated solu- 

 tion, and after acting for twenty-four hours drops were weighed out 

 and cultivated. 



The colonies developed at the end of five days were noted to be 

 about one-half composed of fungi, and to equal 48,936 per gram of 

 the original sewage, which, as previously stated, contained 1,490,000 

 per gram. 



Terebene. — 20 c.c. of terebene were added to 100 c.c. of sewage and 

 digested with frequent agitation for twenty-four hours at the common 

 temperature. In this way the sewage was saturated with as much 

 terebene as the conditions would allow, the excess separating and 

 floating in an upper stratum. A small quantity of the lower liquid 

 was transferred to the weighing bottle, and some drops weighed out 

 for cultivation. 



At the end of four days the number of colonies were only equal to 

 83 per gram of the original sewage, nor did any fresh colonies make 

 their appearance even after keeping the cell in the moist chamber for 

 ten days. 



Potassic Permanganate. — Two flasks, each containing 1 gram of 

 crystallised permanganate, were submitted for twenty-four hours to 

 different temperatures, viz., the one at 18°, the other in an incubator 

 set at 37°. 



The sewage nsed was the same as in the former experiments, and 

 contained over a million and a quarter of centres of growth when 

 cultivated in its normal state. 



The sewage and permanganate which had been placed at the lower 

 temperature yielded on cultivation colonies of micro-organisms equal 

 to 171 to the gram, but that which had been incubated at 37° showed 

 no sign of growth. 



Ammonia, hydroxylamine, wiethylamine, ethylamine. — Solutions of 

 ammonia, hydroxylamine, methylamine, and propylamine were made 

 twice the strength of normal ; that is to say, that double the equi- 

 valent of ammonia (17), of hydroxylamine (33), &c, was dissolved 

 in a litre of water. To one volume of each of these solutions one 



VOL. xxxix. T 



