210 ANNUAL OF SCIENTIFIC DISCOVERY. 



transparencies on glass for the magic lantern and other purposes. 

 There are no colors more dazzlingly bright than the aniline dyes, and 

 they are as permanent as any others of a similar tint. 



Coagulation of the Blood. At the last meeting of the British Asso- 

 ciation, Dr. Davy detailed a large number of experiments made to test 

 the hypothesis brought forward by Dr. Richardson, that the coagula- 

 tion of the blood mainly depends on the escape of ammonia. The 

 many results described by the author were opposed to this view. 

 First he showed that blood in its healthiest state contains no appre- 

 ciable quantity of the volatile alkali ; and, secondly, that ammonia 

 added to the blood in a notable quantity did not arrest the change. 

 The conclusion finally arrived at was that we are yet ignorant of the 

 cause of the phenomenon, and that the hypothesis of Dr. Richardson 

 if acted on in medical practice must be attended with risk. 



A new Drop-Counting Apparatus, invented by M. Salleron, is 

 figured and described in the Repertoire de Clrimie, accompanied by 

 a table giving the names of liquids at the temperature of plus fifteen 

 degrees Cent., the weight of one drop of each in grammes, the num- 

 ber of drops equal to one gramme, and the weight of twenty drops. 

 The apparatus is composed of a small flask, with a side tube, by 

 which the liquid is poured out. The diameter of the spout from 

 which the liquid falls drop by drop is determined for the weight of a 

 drop of distilled water, i. e. five centigrammes. Twenty drops of 

 water thus collected weigh then exactly one gramme ; and this exact- 

 ness, it is said, is so great that these twenty drops always give the 

 same weight, if care be taken to dry the external edges of the tube 

 every time that the liquid is made to flow. The form and capacity 

 of the flask may vary, but not the diameter of the exterior side tube, 

 which constitutes a true and precise instrument. We give a few 

 results : The number of drops of distilled water for a gramme being 

 20, the number for the same weight of nitric acid will be 27 ; of sul- 

 phuric ether, 90; of laudanum, 34; of chloroform, 60; of tincture 

 of rhubarb, 54, etc. 



Healthfullness of fresh Paint in Apartments. M. Leclerc, a well- 

 known house-painter in Paris, has made several experiments to ascer- 

 tain whether emanations from certain paints containing such sub- 

 stances as white lead, zinc white, linseed oil, essence of turpentine, 

 coal oil, essence of lavender, etc., are injurious to health. He caused 

 the inside of some boxes to be painted, and within them he placed 

 wire cages containing rabbits, which were not in contact with the 

 paint, but only subject to the influence of the emanations from it. 

 The rabbits suffered while the paint was fresh, especially when it con- 

 tained coal oil, but none of them died. It is thus proved that living 

 in apartments recently painted, and which emit the odor of the oil 

 of turpentine, is not permanently injurious to health. M. Leclerc 

 made, also, some other experiments, for the purpose of obtaining de- 

 posits of these emanations from the fresh paintings of houses. 

 Instead of rabbits he placed plates containing a small quantity of 

 water in these chests. After the water had evaporated from the 

 plates he found some remarkable crystallizations like needles, which 

 consisted of combinations in which the oils or essences employed 



