198 Miscellantes. 
M. Robiquet ascertained it to deserve. Concluding that it was metallic, 
it was also concluded that it must be chloride of silver, from its color 
and characters; on boiling the cloth in ammonia however no silver or 
chloride of silver was dissolved—the color indeed, became bright- 
er. On incinerating the substance, and digesting the ashes in am- 
monia, and then in nitric acid, both solvents dissolved silver, the 
firsthaving taken up muriate of silver, and the latter having dissolved 
the metal. As if it was not likely that any chloride would be de- 
composed and brought into the metallic state by incineration, it was 
supposed that the silver had been applied at first as a nitrate, and 
then converted into a chloride; the parts which had penetrated 
deepest having escaped the converting action. Imitations of the dye 
were therefore made by dipping the cloth first into a solution of ni- 
trate of silver, then drying it, immersing it in a solution of a muriate 
or chloride of lime and immediately upon withdrawing it, exposing 
it to light: the color was at once developed, and the success was 
perfect. By using different strengths of solution of silver, different 
tints were obtained. 
Upon trying the application in a large way, a curious cause of 
failure occurred. Unless the whole. be exposed to the light at once, 
the color is not uniform; the parts exposed at different times are 
dissimilar, and hence cloudiness is produced. This may be obvi- 
ated in some situations, but not in others where space is limited. 
In printed goods it is supposed that some good application of the 
idea may be made.—Jour. of Roy. Inst. No. 3. 
2. Purple Precipitate of Silver, Gold, §-c.—(Poggendorf’s Annals.) 
—Fischer has shewn that proto-salt of tin yields, with solutions of 
silver, platina, palladium, and tellurium, precipitates similar to those 
produced with solution of gold. Frick has shewn that silver precip- 
itate may be prepared of great purity, by using a very pure proto- 
nitrate of tin, and after adding it to the solution of silver, adding also 
dilute sulphuric acid. ‘The addition is supposed to prevent the fur- 
ther oxidation of the tin by the free nitric acid, and so also the pre- 
cipitate. ‘The proto-nitrate of tin is to be prepared by decomposing 
the proto-muriate by nitrate of lead. In the purple precipitate of 
silver, the combustion is as strong as in Cassius’s purple ; the sub- 
stance is not decomposed either by muriatic acid or ammonia. In 
preparing the purple precipitate of Cassius, Fischer who first pomted 
out the superiority of the proto-nitrate of tin in the above experi- 
