UNINFLAMMABLE STUFFS. 555 



reliable data for commercial operations. As a preliminary, the character 

 of the fibre ought to be determined in the laboratory. 



1st. In relation to its structure, having in view ease in fibrous sepa- 

 ration. 2nd. In relation to its chemical constitution, having in view 

 ease in bleaching. 



Bleached half-stuff would realise a larger profit than unbleached, 

 always supposing that the process of bleaching, owing to the accident of 

 geographical position or otherwise, did not entail expense extra to that 

 properly belonging to the -operation under the most favourable circum- 

 stances. 



Fibre could be sent into the market as half-stuff unbleached when- 

 ever its characteristics were reliably established. 



B. L. 



UNINFLAMMABLE STUFFS. 



On this important subject the French Academy of Sciences has 

 received a report from MM. Payen, Velpean, and Bayer, in which M. H, 

 Chevalier's paper sent in to the Academy on the 25th of January last, is 

 discussed. From this report it appears that only three salts have 

 hitherto been found that may be successfully applied to the purpose in 

 question, viz., that of -preventing ladies' dresses from catching fire. 

 There are many other salts that would do the same, but not without 

 spoiling the dye, or the gloss, or the texture of the stuff, &c. Of the 

 three in question, the sulphate and phosphate of ammonia have the in- 

 convenience of being decomposed by the heat of a smoothing-iron ; but 

 they are applicable in those manufactures where stuffs are stiffened by 

 the action of hot air or cylinders heated by steam. They exercise no 

 action upon either the thread or the colour of the stuff. The phosphate 

 of ammonia may be mixed with half its weight of hydro-chlorate of 

 ammonia. To obtain an efficacious solution, 20 per cent . of this mix- 

 ture must be dissolved in water. A solution of 7 per cent, of sulphate 

 of ammonia produces the same effect, and is therefore the most econo- 

 mical salt that the trade can employ. But in those cases in which the 

 smoothing-iron cannot be dispensed with, as in linen, for instance, a 

 solution of 20 per cent, of tungstate of soda should be preferred. To 

 obtain the desired effect all these solutions must be applied to the stuffs 

 after they have been stiffened and dried, because starch is always used 

 in a weaker solution than that required for these salts. Acid tungstates 

 destroy the thread of cotton stuffs, like borax, alum, and other sub- 

 stances previously recommended. The tungstate of soda is prepared in 

 Cornwall, where the tin mines yield a large quantity of wolfram. It 

 costs from 12?. to ISl. per ton. The sulphate of ammonia costs about 

 14?. per ton, and has hitherto been used for manure. 



