forming Hyper -manganate of Potash. 299 



the above process, a quantity of crystals equal in weight to 

 one-third of the oxide employed. 



The mother liquids, on the addition of sugar, yield a 

 large quantity of hydrated peroxide, which, with that 

 separated by decantation, is very well adapted for a new 

 operation. 



In this process, while the chlorate is economized, and 

 the quantity of hyper-man gan ate increased, that of the 

 chloride of potassium is diminished, and only half of the 

 oxygen is lost. 



I have no doubt, that, if the green mass be dissolved in 

 a small quantity of cold water, and the solution evaporated 

 in vacuo, the green manganate of potash may be obtained 

 with equal facility. 



Where it is necessary to filter these solutions, as paper 

 cannot be employed, I am in the habit of using a funnel, 

 the throat of which is stopped with Asbestus, which answers 

 the purpose perfectly. 



I have the honour to be, 



Your obedient Servant, 



WILLIAM GREGORY. 



10, Ainslie Place, Edinburgh, 

 September, 13th, 1836. 



Article VI. 



Analysis of Tartar Emetic. By Mr. Thomas Richardson. 



Mr. Phillip's analysis of this salt differing from Dr. 

 Thomson's in the proportion of the water it contains, I was 

 induced to repeat the experiments of the latter gentleman, 

 employing the same specimen. 



The analysis was conducted in the following manner: 



1. 25 grs. were heated for a considerable time, on the 

 sand bath at the temperature of about 400° Fah. and lost 

 1*21 grs. or 4-84 per cent. 



2. What remained was dissolved in water, and a current 

 of sulphuretted hydrogen passed through the solution till 

 all the antimony was thrown down. The precipitate, after 

 being well washed and dried, weighed 13'3 grains. But 

 11 sesquisulphuret of antimony : 8 antimony :: 13-3 : 

 9*67 grs. = 11 '48 grs. oxide of antimony. 



3. The liquid and washings from the above precipitate 



