1813.] 



Account of a compound Salt. 



367 



melts, and gives out muriatic acid, if the temperature be in- 

 creased. 11. It is decomposed by solution in vi^ater ; muriate of 

 lead precipitates ; sulphate of soda crystallizes on cooling ; and 

 muriate of manganese remains in the mother water. 12. When 

 digested with sulphuric acid, copious fumes of muriatic acid gas 

 are disengaged. 



Having ascertained by a number of experiments that this 

 salt is composed of sulphate of soda, muriate of manganese, 

 and a small quantity of muriate lead, the following were 

 made to discover the proportions of each : — 



I. One hundred grains of this salt added to a quantity of water 

 at the temperature of 60° quickly dissolved, except a small 

 portion of a dense white matter which remained at the bottom 

 of the vessel, and a few particles of a brown substance that 

 more slowly subsided. The white matter was washed with cold 

 water, and exposed to a low red heat, when it fused : in this 

 state it weighed 1*5 grain. It was found to be soluble in a large 

 quantity of boiling water, which on cooling deposited minute 

 crystals of a pearly lustre ; sulphate of silver added to a solution 

 of these crystals, occasioned a white flaeky precipitate ; sulphate 

 of soda deposited a heavy white powder ; and the alkalies preci- 

 pitated a white substance, which, on exposure to a red heat with 

 charcoal, yielded a globule of metal resembling lead. The 

 white insoluble matter is therefore muriate of lead, and, accord- 

 ing to the analysis of Kirwan, is composed of 



•25 acid. 

 1*25 oxide 



The light brown precipitate, when collected and exposed to a 

 red heat, weighed '5 grain. 



On a larger quantity being procured, it was found to be solu^ 

 ble in muriatic acid; the solution yielded a yellowish white 

 precipitate, with triple prussiate of potash; and the alkalies 

 deposited a white substance, which quickly turned brown on 

 exposure to the atmosphere, or on being heated ; properties 

 belonging to the oxide of manganese. 



II. One hundred grains of this salt were dissolved in water, 

 and the solution separated from the insoluble matters ; muriate 

 of barytes was added to the solution as long as any precipitate 

 continued to be formed ; the precipitate was then well washed 

 and ignited ; it weighed 93 grains, which indicate 54-7 grain? 



^ of sulphate of soda, that are, according to Kirwan, composed of 



30-63 acid . 

 24-07 alkali 



III. Sulphate of silver was added to a solution of 100 grains 

 Qf this salt until it ceased to form a precipitate ; the edulcorated 



2 



