SELECTED ARTICLES. 43 
8th is a little reddened, it may be inferred that this vinegar owes 
one-third of its sourness to a foreign acid. If it has already 
been determined that it is the sulphuric, the quantity of aceto- 
metric liquid employed to saturate them is calculated, and in 
this way the proportions of sulphuric acid per litre which have 
been added, are obtained. 
These experiments and calculations may appear a little diffi- 
cult to those unacquainted with chemistry. \ 
Nitric and muriatic acids can be detected in vinegar by sa- 
turating it with subcarbonate of soda, filtering and crystalliz- 
ing. If the acid is muriatic, there will be found with the 
acetate of soda, a salt possessing a very saline taste, and in 
cubic crystals, while the other salt crystallizes in prisms. The 
proportion of muriatic acid can be determined by dissolving 
these salts and adding nitrate of silver. From the precipitate 
obtained, the weight of the muriatic acid may be calculated, 
from a knowledge of the constituent proportions of nitrate of 
silver. 
If the sophistication is made by nitric acid, which is ex- 
ceedingly rare, in consequence of the high price of this acid, 
a nitrate of soda is obtained, crystallizing in rhomboidal 
prisms, along with an acetate. The first salt has a cooling 
taste; it fuses upon coals like salt petre. The quantity of 
nitric acid can be determined by drying these two salts, and 
treating them with concentrated alcohol, which dissolves the 
acetate without touching the nitrate. From its weight the 
quantity of nitric acid is determined by its constituent princi- 
ples. 
It may happen that in commerce, muriatic or acetic acids 
may be mixed with sulphuric acid: to detect this last, a piece 
of linen or of paper should be dipped in the acid to be tested, 
it is then to be dried by the fire; if it is carbonized, it is an 
indication of the presence of sulphuric acid. It is evident, as 
a consequence, that there will be a want of precaution and of 
prudence, if free washing is dispensed with, after the employ- 
ment of acids, both in bleaching and in brightening blue co- 
lours. 
