Chemistry. | 111 
the sulphate of potash by the atomic weight of potash, from the quotient 
obtained, by dividing the atomic weight of sulphate of soda by the 
atomic weight of soda. 
The amount of soda may be ascertained, if the sum of the weight 
of the two bases be multiplied by the quotient obtained on dividing the 
atomic weight of the sulphate of potash by the atomic weight of pot- 
ash; and from the product thus obtained the weight of the two salts is 
subtracted, and what is left is divided just as in the case of the potash. 
It will be best understood when expressed in the following way : 
K, the quantity of potash. 
N, sa soda. 
8, fi two salts. 
b, ¥ two bases. 
q, quotient obtained by dividing the atomic weight of sulphate of pot- 
ash by that of potash. 
q', quotient obtained by dividing the atomic weight of sulphate of s0- 
da by that of soda. 
S—bq' bg—S 
Thus, k= ;“and N=o yr 
It is evident that g, q' and g—q’ are unchangeable quantities, q be 
ing equal to 184955, q/=2-28209, and g—q'=—0°43254. An exam- 
ple will render this much clearer. Let us suppose that the two sul- 
phates weigh together 100 grains, the sulphuric acid (determined by 
baryta) 48 grains ; consequently the two bases must weigh 52 grains. 
To find K, (the weight of the potash,) é (the weight of the two bases) 
—=52 we multiply by g’=2'28209, and then subtract the product ob- 
tained —118-66868 from S (the weight of the two salts) =100, and 
divide the rest ——18-66868 by q¢—q'=—0°43254, by which 43°15 
are obtained. These 43°15 of potash, to be converted into neutral sul- 
phate of potash, will require 36°63 sulphuric acid. N (the weight of 
soda) can be ascertained by substituting the proper numbers for the let- 
ters in its formula, when it will be found to be 8°83, equivalent to 20°17 
sulphate, which added to the sulphate of potash, furnish 99-95, the orig: 
inal amount being 100 grains.* J. LS. 
22. Purifying Arseniferous Sulphuric Acid during its Manufae- 
ture; by A. Dupasquizr, (Compt. Rend., March, 1845, p. 794.)—In 
much of the sulphuric acid prepared from pyrites or from the sulphur 
obtained from pyrites, arsenic is present in the proportion of from 1 to 
14 thousandths. The author recommends the use of the alkaline sul- 
* This method I have found accurate and very easily performed ; and if upon’ ; 
more extended experiments its accuracy be found to hold out, the analyst will re- 
quire no better method. 1.4.5. 
