Process for metallizing Potash and Soda. 283 



1. It is soluble in distilled water, and its solution does 

 not alter the tincture of turnsole or the syrup of violets. 



2. It is precipitated black by lime water, and gray by 

 ammonia. 



Preparation of the mild Muriate of Mercury. To convert 

 the sulphate of mercury into calomel, mix intimately, on a 

 porphyry stone, equal parts in weight of the sulphate of 

 mercury as above designated at the minimum, and of sea 

 salt purified and dried : introduce the mixture into matrasses 

 with flat bottoms two- thirds of which are left empty, and 

 proceed to sublimation in the usual way. After the opera- 

 tion, which lasts five or six hours, there will be found in 

 the arch of the subliming vessel a loaf of calomel of the 

 weight of about 30 ounces, if four pounds of mixture are 

 operated upon. This salt is as white as that of commerce, 

 and purer than that which we commonly meet with as 

 coming from the laboratories of Switzerland. 



In order to add to its purity, particularly when the heat 

 has not been well managed, the author of the memoir pro- 

 poses the following method, which perfectly succeeded with 

 jiim, and which has the advantage of having no action on 

 the mercurial salt. 



Purification of Calomel. Pulverize the calomel in a 

 mortar of marble or of hard stone. Pass it through a fine 

 hair sieve in order to obtain a homogeneous powder tole- 

 rably fine. Introduce the pulverized salt into matrasses of 

 the same form as in the foregoing operation : afterwards 

 cover it with a' layer about two lines thick of fine sand, pre- 

 viously washed with water slightly sharpened with muriatic 

 acid, in order to free it from the carbonate of lime and 

 oxide of iron which are mixed with it, and sublime as be- 

 fore directed. The calomel purified by this process is very 

 pure. M. Planche has presented to the Institution a loaf of 

 it very regularly crystallized, and in whiteness equal to that 

 of corrosive sublimate. 



LV. Description of a Process hy means of which we may 

 metallize Potash and Soda without the Assistance of Iron. 

 By M. Curaudau*. 



A he decomposition of the alkalis, which I have never re- 

 garded as simple bodies, having been long an object of my 

 inquiries, I became anxious to repeat the experiment ac- 

 cording to which Messrs. Thenard and Gay Lussac have 



• Jitn&les de Chimie^ tome lxvi, p. 97. 



announced 



