f82 Process for the Preparation of Muriate of Mercury. 



closes of corrosive sublimate, and of metallic mercury, which 

 ought to be used in this preparation ; M. Planche, after nu- 

 merous trials, has ascertained that it is sufficient, in order 

 to obtain calomel, to sublime a mixture of sulphate of mer- 

 cury at the ininimum, and of dry muriate of soda. 



Preparation of the Sulphate of Mercury. Introduce into 

 a stone retort placed in a reverberating furnace one part of 

 crude mercury, and one part and a half of sulphuric acid 

 at 66° of Baume's areometer. Fix an adopter and a tubu- 

 lated receiver to the retort, which must be made to com- 

 municate either with distilled water contained in Woulf's 

 flasks, if we wish to collect the sulphurous acid; or with 

 the external air, if the situation of the place admit of the 

 gas being set at liberty. Gradually heat the retort until the 

 acid boils, and keep up the fire while the acid vapours are 

 disengaged in abundance, taking care to slacken it towards 

 the end of the operation, i.e. when the drops of the liquid 

 which passes from the retort into the bell-glass succeed 

 each other slowly, and when there is a diminution of the 

 white vapours. After this operation, which lasts four or five 

 hours, the retort may be broken ; or, rather, we may sepa- 

 rate by means of tongs the sulphate of mercury, which is 

 easily detached. 



The acid sulphate of mercury thus obtained is very white 

 and very friable ; it passes to the yellow colour on the ad- 

 dition of the most trifling quantity of cold water. In or- 

 der to carry this salt to the state of sulphate at the minimum, 

 the author combines it with quicksilver in the following 

 manner. 



He takes 18 parts of the above acid sulphate of mercury, 

 and eleven parts of mercury. He triturates them together 

 in a mortar, or in a porcelain capsule, adding by degrees 

 six parts of cold water. 



The first portions of water make the sulphate assume a 

 yellow colour, which soon disappears on shaking it. Heat 

 is developed. The matter assumes a very deep gray co- 

 lour. After a few minutes trituration, he adds a sufficient 

 quantity of water to give to the whole the consistence of a 

 thick broth ; and he continues to triturate until the mass 

 has become of a dirty white, and the mercury has totally 

 disappeared, which lasis for five or six hours when the mass 

 is considerable. He afterwards dries this substance in a 

 stove at a temperature of 30° to 35° of Reaumur. 



M. Planche is of opinion, that the mercurial mass which 

 results from this operation is in the state of sulphate at the 

 minimum, and he proves it by the following experiments. 



1. It 



