Chemical Science. 405 



poured indifferently to each other, a precipitate is obtained quite 

 different from the borate of silver. It is brown, insoluble in water, and 

 when well washed proves to be oxide of silver ; by heat it loses 9 per 

 cent, of oxygen and water. 



Thus, whilst a concentrated solution of borax produces a subsalt 

 from a solution of silver, the effect of the boracic acid is entirely lost 

 by mere dilution, and the solution acts, with respect to silver salts, 

 as pure alkali. This effect of water cannot be compared to that upon 

 bismuth salts or verdigris, for the subborate of silver is entirely 

 soluble in water. 



Solution of borate of potassa acts in the same manner. Borate of 

 ammonia in strong solution gives, with nitrate of silver, a white 

 soluble precipitate, and, when diluted, it produces no precipitation. 

 Sulphate of silver acts in the same manner as the nitrate *. 



14. IGNITING PLATINA. 



Dr. Hare says, ' I find that if asbestos or charcoal be soaked under 

 an exhausted receiver in muriate of platina, then dried in an evapo- 

 rating oven for twenty-four hours, and afterwards ignited, the property 

 of ignition in the gaseous elements of water is acquired f.' 



15. ON ORGANIC ANALYSIS, AND ON THE CONSTITUENTS OF 

 VARIOUS ORGANIZED BODIES. 



MM. Henry and Plisson have been very earnestly employed for 

 some time past in endeavouring to improve the means of analysing 

 organic bodies, so as to obtain accurate estimates of the proportions 

 of their elements, and for this purpose have exerted themselves to 

 give the element under consideration, whether oxygen, hydrogen, 

 carbon, or azote, a gaseous form, conceiving that the probable errors 

 in the mensuration of gases are far smaller than those likely to occur 

 in the estimation of weights. Their processes have been published 

 in several memoirs in the Journal de Pharmacie, and elsewhere, and 

 they have finally given an account of the results of many analyses 

 obtained by their methods, which it is our intention to abstract or 

 transcribe. 



The substances were used in the purest possible state ; for they 

 W ere i. Prepared with great care and crystallized many times, 

 ii. They were calcined to ascertain the absence of inorganic matter, 

 iii. They were carefully dried at 212 F. iv. The mixtures of the 

 principles and oxide of copper were always preceded in the tube by 

 an extensive portion of pure oxide of copper, heated powerfully, so as 

 to decompose the carburetted hydrogen and oil formed upon the first 

 action of heat on the destructible matter, v. The tube and com- 

 pound were always placed in the most favourable circumstances for 

 the avoidance of errors. 



* Ann. de Chimie, xlvi. 319. f Sillimau's Jour., xx. 1 GO. 



