Intelligence and Miscellaneous Articles. 413 



dissolved in water by potash, is the salt described by Sdnillas under 

 the name of chlor-iodate of potash, and composed of bi-iodate of 

 potash and chloride of potassium. — Journal de Pharmacie, August, 

 1839. 



CHLORO-STANNITE OF MERCURY. 



M. Capitaine gives this name to the white matter which sublimes 

 when chloride of tin is formed, by the combination of the protochlo- 

 rides of tin and of mercury. 



The best process for preparing it is the following : take 24 parts 

 of protochloride of mercury, and 3 parts of tin amalgamated with a 

 portion of the mercury. These quantities correspond to rather less 

 than two equivalents of the protochloride to one equivalent of 

 tin. These substances after being thoroughly mixed are to be put 

 into a retort capable of holding four times the quantity, on account 

 of the swelling up which occurs when the action begins ; when the 

 retort is heated by a few coals, the action soon takes place with a 

 slight noise, the cessation of which shows that the action is complete. 

 When the retort is cold it is to be broken, and it is found to contain 

 a grey substance, which is frequently spongy ; and beneath this there 

 is some mercury, which separates during the action. This grey matter 

 is to be pulverized and put into a flat-bottomed matrass, which is to 

 be heated to about the boiling point of mercury. Bichloride of tin 

 is vaporized, and the chloro-stannite of mercury sublimes, and 

 there remain in the matrass anhydrous protochloride of tin, and some 

 mercury. 



When white vapours cease to arise in notable quantity, the opera- 

 tion is to be stopped ; when the matrass has cooled, it is to be cut at 

 about an inch from the bottom, and the upper part will be found 

 studded with white dendritic crystals of chloro-stannite of mercury ; 

 these are to be removed with feather, and kept in a well-stopped 

 bottle, for they attract moisture from the air. 



The properties of this substance are, that it is perfectly white. It 

 is volatile, but its point of volatilization is simultaneous with that of 

 its point of decomposition, so that it cannot be volatilized unchanged. 

 When it is heated a portion only sublimes, the remainder is decom- 

 posed into metallic mercury, protochloride of tin, and perchloride of 

 tin, which may be collected. 



When this substance is treated with water, it becomes grey, and 

 then black ; this happens because the protochloride of mercury is 

 reduced by the protochloride of tin. 



In analysing this substance the determination of the mercury is 

 readily effected ; it is necessary only to take a known weight of it, 

 and to boil it for a short time with water acidulated with hydrochlo- 

 ric acid, to which it is better to add a little protochloride of tin, in 

 order to be sure that the whole of the mercury is reduced to the 

 metallic state ; the chlorine and tin are easily determined : when the 

 salt is treated with carbonate of soda, there are produced oxide of 

 tin, oxide of mercury, and chloride of sodium ; when the whole is 

 thrown on a filter, the liquor passes through, at first clear, but if 

 the filter be washed with pure water, oxide of tin passes through 

 with it, lu grder to prevent this, the filter, after the solution has 



