124 Notice of some Recent [Feb. 



After being heated in a platinum crucible, by which 

 operation it first became brown and gave out smoke, it 

 assumed a white appearance and weighed 0*41 grm., ac- 

 quiring no change by treatment with nitric acid. This 

 product is the apocrenic acid combined with the sulphate 

 of lead. Now as the weight of an atom of sulphate lead is 

 to the crenate of lead as 41 to 59, the atom of crenic acid 

 is 1333*4. By analyzing the crenate of lime Berzelius 

 obtained for the atomic weight of the acid 1358*38.* 



Apocrenic Acid. — Apocrenate of copper is precipitated 

 when the ochre has been treated with potash, and acidified 

 by acetate of copper. This is washed twice with cold water, 

 It is then to be mixed with a little water and a stream of 

 sulphuretted hydrogen passed through it. The solution is 

 dark brown, and by concentration blackish brown. By 

 absolute alcohol the pure acid is taken up and freed from 

 the salts. A small portion remains on the filter with the 

 sulphuret. This is taken up by acetate of potash, the 

 solution evaporated, and the apocrenic acid dissolved in 

 alcoholofsp.gr. 0*864. The acid may then be separated 

 from the potash by means of muriatic acid. 



To ascertain the atomic weight, apocrenates of lead and 

 barytes were analyzed. By the former the numbers were 

 1693*0, and by the latter 1642*2.f 



Action of Formic Acid upon some oxides and peroxides of 

 metals. — 1. Gobel finds (Schweigg Seidel, vii.) that solutions 

 of gold, platinum, and palladium are not decomposed by free 

 formic acid even at the boiling point. This acid volatilizes 

 gradually without separating the least trace of metal ; but 

 the formate of soda completely precipitates these metals 

 partly in brilliant spangles, and partly in the form of powder. 

 The solutions of nitrate of silver and mercury are decom- 

 posed by free formic acid ; but the decomposition is more 

 rapid by means of the alkaline formate. 



2. The red oxide of mercury affords an easy method of 

 determining the quantity of free formic acid, either mixed 

 with other acids or combined with bases. The proportion 



* If we reduce these weights to convenient numbers, we have for a mean 

 13*458 which approaches 13-5 so nearly, that we can have no hesitation in admit- 

 ting itas the atom of crenic acid. — Edit. 



t 16-75 appears, therefore, the atom of apocrenic acid.— Edit. 



