THE .ANALYST. ON A NEW METHQD FOB THE ESTIMATION OF SULPHURIC ACID I N VINEGAR, &c. BY W. C. YOUNG, F.C.P. Read hefore the Society of Public AmdystS ojz 14th Nol;ember, 1877. THE methods most commonly used for the determination of sulphuric acid in vinegar consist in either estimating the total sulphuric acid as sulphate of barium and deducting from it the amount found as sulphates in the ash, or in taking the acidity of the vinegar after evaporating the acetic acid on B water bath.The first of these methods is open t o the objection that all chlorides present are converted into sulphates, thus taking up part of the eulphuric acid originally present in the free state. I n the second method I have found great difficulty in driving off the acetic acid without charring some of the organic matter and consequently forming sulphurous acid; in addition, the objection t o the former method applies equally to this, as any hydrochloride acid formed by the action of the sulphuric acid upon the chlorides present would be volatilised.It occurred to me to take advantage of the decomposition of chlorides by sulphuric acid to estimate the quantity present by determining the amount of hydrochloric acid liberated.This I do in the following manner:-To 30 C.C. of the vinegar under examination is added an excess of chloride of barium and the liquid made up to any convenient bulk; in one-third of the liquid (which is equal to 10 c c. of the vinegar) is estimated the total chlorine by standard solution o f nitrate of silver after carsfully164 THE ANALYST.neutralisiag with weak caustic soda solution ; the remaining two-thirds is evaporated to dryness, carefully iminerated, and the chlorine in the ash estimated as before. The difference between the two results calculated for the same quantity of vinegar is due to hydrochloric acid volatilised, from which the sulphuric acid may be deduced by calculation. I have made many trials of this method and have obtained uniformly exact results, i t takes but a short time and indicates only the free sulphuric acid added. It is of course applicable to lime juice or lemon juice.