Chemical Science. 227 
dently the re-action of pure boracic acid. Concentrated phos- 
phoric acid gives a rose-colour, which, on the absorption of 
humidity from the air, changes slowly to orange. Diluted 
with from 10 to 30 parts of water, it affords, in half a minute, 
avery fine yellow colour, which is preserved always without 
alteration. Phosphatic acid resembles phosphoric. Hypo- 
phosphorous acid gives also a red colour, which passes through 
pale yellow to white. Diluted, it gives a fine but fugitive 
yellow. Concentrated arsenic acid produces a rose colour, 
which continues for a long time. Diluted with from 10 to 30 
parts of water, it affords, at the end of a minute, a very fine 
yellow colour, but it loses its brightness in a few minutes, 
becoming permanently pale-yellow. Arsenious acid gives no 
distinct re-action. Concentrated acetic acid gives instantly a 
sombre yellowish colour, which immediately disappears, and is 
succeeded by a pale violet colour, which, viewed by transmitted 
light, is a very deep violet-red. Diluted with more or less 
water, it affords at first a colour somewhat yellowish, and then, 
both by reflected and transmitted light, a violet-red colour. 
Sulphurous acid, mixed with the{acetic, destroys its action, or at 
least weakens it; and sulphuric acid occasions it to give a 
yellowish colour, instead of the violet-red. An acetic acid, 
which contains no more than 0.005 of sulphuric acid, affords 
a very perceptible yellowish colour. Citric acid, strong or 
dilute, gives a beautiful and durable yellow. ‘Tartaric acid 
occasions also a fine yellow, which soon weakens and becomes 
dirty, according as the acid is diluted. Malic acid resembles 
tartaric in this respect. Concentrated oxalic acid produces an 
orange-colour, becoming slowly yellow. Diluted, it gives a 
good durable yellow. Succinze acid gives a somewhat 
yellowish colour, which soon fades. Benzoze acid has almost 
no action on Brazil-wood paper. Woollen-cloth, plunged into 
a boiling bath of Brazil-wood, then drained, and then dipped 
for some minutes in a dilute phosphoric or citric acid, or, 
what is cheaper and equally good, a dilute bi-phosphate of 
lime, takes a very lively yellow dye which resists washing with 
soap. Silk may be dyed by the same process, but cotton and 
linen did not give satisfactory results.—Annales de Chim. et 
de Phys, xix, 283. 
2. The Manufacture of Wine wmproved by Chalk.—Count 
Alexander Czacki, after an experience of four years, recommends 
the addition of a little chalk to the must of grapes, when it is 
somewhat sour; for the acidity being due to citric and tartaric 
acids, there is thus formed a precipitate of citrate and tartrate 
of lime, while the must becomes sweeter, and yields a much 
finer wine. Too much chalk may render the wine insipid, 
since it is proper to leave a little excess of acid in the must. He 
Vor, XIV. 
