A new Red Dye for Dyeing Wool. 123 
direct positive proofs. This effect will not take place if the proof has 
been carefully washed afier leaving the bath of sulphate of iron; still 
the decomposition of the hyposulphite S$ on spontaneously, and 1 
new red dye for dyeing wool.—On treating uric acid with nitric acid 
and then with ammonia, Proust obtained, at the beginning of this cen- 
tury a red substance which he called purpurate of ammonia. M. 
Wohbler and Liebig have since studied this substance and separated a 
compound of a fine red color represented by the formula C12N®H®O8, 
Thi 
which they call murexid. This material, which is easily prepared 
: 
T € red of murexid fixes itself on the wool without a mordant. 
After imbibing the alloxane, a bit of wool drying exposed then to am- 
moniacal vapors and afterward to the heat of a steam dram heated 
ron, the red color is seen to be immediately developed. It is indis- 
on murexid, 
Although this color requires no mordant, M. Schlumberger has how- 
; ver found that a mordant may be useful. That which he prefers is a 
bath Consisting of equal parts of bichlorid of tin and oxalic acid, the 
— forming with water a solution marking 1° Beaumé. The mor- 
nts made with protochlorid of tin give indifferent results. : 
Under the pie of the sun’s rays, the Commission found the red of 
murexid to be more stable than that of cochineal, and they do not hesi- 
to recommend the use of it in dyeing gobelins in preference to 
“ochineal, although the new red is just now dearer than the old, since 
n heated ; water rerioves this last, while it is wholly without action. 
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