I 



of Processes in the Fine and Useful Arts. 167 



This salt appeared to have cost in England one hundred 

 francs the kilogramme, (S lbs. 3 oz.) but could be prepared in 

 France for thirty-six francs, reckoning the iodine to cost forty 

 francs. 



" It appears to me (observes this skilful chemist) that this 

 salt ought to be applied to the stuff before it is passed through 

 hietallic solutions. Among the latter, those which give the 

 most beautiful colours are the solutions of lead and mercury. 

 This salt may be applied with advantage to stuffs by the aid 

 of a solution of starch which becomes a beautiful violet, (a 

 known effect of iodine and starch.) The starch appears also 

 to contribute to fix the salt on the stuffs. 



" There is another salt also much employed, it is said, in 

 Glasgow, in calico-printing, which I ought also to mention, 

 because it appears not to be much used in France. This is 

 a triple acetate of lime and copper, prepared in the large way 

 by Ramsay, at Glasgow, for the printers. This salt is of a 

 very beautiful blue. It crystallizes in straight prisms with 

 square bases. The summits of the prisms are often replaced by 

 facets, whence result prisms with six or eight planes, according 

 tb the extension which the secondary faces acquire. 



When this salt is decomposed by a fixed alkali, the oxide 

 of copper and lime are precipitated combined, because they 

 meet in the nascent state and in definite proportions. It is 

 certain that the precipitate turns green but little in the air, 

 even in drying, and in its application it is a kind of ash blue 

 which becomes fixed on the stuff. I call the attention of cot- 

 ton printers to this salt, which may furnish very beautiful 

 dyes, and which cannot become very expensive. — Bulletin 

 S' encouragement, Sept. 1828. 



4. Account of M. Gersdorff'^s manufacture of Packfong. 



This substance, as analysed by M. Brewster, * is composed 

 of 31.6 parts of nickel, 25.4 of zinc, 40.4 of copper, and 2.6 

 of iron. It is employed in China in the fabrication of a great 

 number of utensils, such as vases, teapots, goblets, &c. It has 

 the lustre, colour and sound of silver. 



M. de Gersdorff^ desiring to introduce into Europe so va- 



* Not bein^ able to refer to the original of this article, we cannoV cor- 

 rect this typographical error, which \i likeJy to be Berthier, 



