246 Phillips' Remarks on the 



proto-nitrate de raercure." It is a very operose preparation and 

 it can scarcely be mere protoxide of mercury, for in this instance 

 the nitrate of mercury is not crystallized, but the solution used, 

 without it ; it must, therefore contain some pernitrate, which 

 will of course form a triple compound with the ammonia. 



The next preparations are peroxides of mercury, one by nitric 

 acid, and the other by heating the metal in atmospheric air ; 

 these do not call for any particular observations. The prepara- 

 tions following these are to be found under the head of muriates, 

 although it is well known, that according to the greater number 

 of chemists, and especially of France, neither calomel nor cor- 

 rosive sublimate contain an atom of this acid, but are chlorides. 

 The first is calomel, called muriate de mercure doux sublime : 

 it is formed by mixing and triturating 48 parts of corro- 

 sive sublimate with 30 of mercury. Now it is stated by Mr. 

 Brande, Manual, p. 299, that corrosive sublimate consists of 

 67 chlorine, and 190 mercury, the proportions to be inferred 

 from Dr. Wollaston's scale are 67 chlorine, and 191.1 mercury : 

 in order, therefore, to reduce corrosive sublimate to the state of 

 calomel, 257 of the former must be combined with 190 of mer- 

 cury, which bear to each other the proportion of 48 to 35.5 

 nearly ; so that by directing only 30 parts of mercury, the wash- 

 ing to which the product is to be subjected, must dissolve nearly 

 eight parts of corrosive sublimate, if they are not previously 

 wasted in sublimation. 



We afterwards find calomel directed to be " divise en poudre 

 trfes subtile au moyen de I'eau d'apr^s la methode de Josias 

 (meaning Joseph) Jewell ;" this very excellent method is pro- 

 perly adopted. 



Calomel prepared by precipitation follows next ; it is formed 

 by dissolving mercury with the assistance of a gentle heat in 

 nitric acid of 20° of Beaume ; that is, of about 1.163 sp. gr. It 

 is, I believe, scarcely possible to prevent the formation of some 

 pernitrate of mercury, and therefore some means ought to have 

 been adopted to prevent its waste, such as adding muriate of am 

 monia after precipitation of the calomel to form white precipitate. 



Corrosive sublimate, under the name of muriate oxigene de 



