568 'ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of ten or twelve miles, is absolutely purified by infusorial 

 animals, aquatic plants, and chemical oxidation. 



The Professor makes a special application of his researches 

 to the Croton water, and states as a general conclusion from 

 the whole that for the supply of cities rivers and lakes are 

 very decidedly superior to wells, which should always be 

 viewed with suspicion, on account of the danger of contam- 

 ination from the drainage of the soil, and leakages from the 

 cess-pools and private vaults. 



PICRIC ACID AS A TEST FOR ALBUMEN IN URINE. 



Picric acid is recommended by Dr. Galij3pe as the best re- 

 agent for the detection of albumen in urine. The urine 

 should be added drop by drop to a few cubic centimeters of 

 a solution of the acid in water, when any albumen present 

 will produce a characteristic cloudiness, not to be confound- 

 ed with any thing else. If the picric acid is added to the 

 urine no reaction will occur. 15 C, VII., 1875, 111. 



SALICYLIC ACID. 



Salicylic acid still continues to find favor as an antisep- 

 tic, supplanting in this respect carbolic acid and other pred- 

 ecessors. How long it will maintain its present position 

 is, of course, a matter of uncertainty. This acid is slightly 

 yellow in color, taking the form of fine crystals, which are 

 readily soluble in alcohol and ether, as also in hot but not 

 in cold water. It melts at 318 Fahr. When heated rapid- 

 ly it is resolved into carbonic and carbolic acids. In addi- 

 tion to its alleged superior efficiency, it is much preferable to 

 carbolic acid in lacking any smell and any unpleasant taste. 



According to Professor Neugebauer, a small quantity of 

 this acid is sufficient not only to prevent the second or after 

 fermentation of wine and its consequent muddiness, but also 

 the formation of fungi in the casks. 



According to Professor Kolbe, half a gramme of the acid 

 will check the fermentation produced by five grammes of 

 yeast in a solution of sugar. It is said to prevent the de- 

 composition of water on shipboard when added in the pro- 

 portion of 1 to 200,000. By covering the bung-hole of the 

 casks with cotton steeped in the acid, the filtration of the 

 air will affect the preservation of the water within the cask. 



