L. TECHNOLOGY. 443 



after washing. How the presence of the oxalate of ammonia 

 prevents the decomposition of the iron salt by prussiate of 

 potash is not definitely known ; but a double salt of oxalate 

 of iron oxide and ammonia probably forms, which is not acted 

 upon by the prussiate of potash. 13 (7, 1871, v., 329. 



DYEING COTTON OF " NATUEE's COLOE." 



Socks, and other fabrics of unbleached cotton, are com- 

 monly dyed with what is called nature's color, a reddish-yel- 

 low tint. The following process has recently been highly 

 recommended as simple, cheap, and durable: Six parts of 

 vesuvin and two of paladin (both aniline preparations) are 

 to be boiled to solution in pure water, and filtered after be- 

 coming cool. A sufficient quantity of this to produce the 

 desired color is added to pure water, with which the articles 

 to be dyed must be thoroughly impregnated. No mordant 

 is necessary, although a little alum may perhaps be added 

 to the bath with advantage. 5 (7, 1871, 88. 



COLOELNG JAPANESE SILK. 



Within the past few years much attention has been direct- 

 ed, both in Europe and America, towards the subject of rear- 

 ing silk-worms of other species than that feeding upon the 

 mulberry, which constitutes the source of supply for a greater 

 part of the silk used in the European and American manufac- 

 tories. The rapid increase in the number of diseases affect- 

 ing the mulberry worm in various stages of egg, caterpillar, 

 chrysalis, and perfect insect, has made it expedient to discov- 

 er substitutes, and of all that have been presented to notice 

 two seem to be favorites the ailanthus worm and that of 

 the oak, or the yamamai of the Japanese. Investigations 

 have lately been made in regard to the chemical and me- 

 chanical peculiarities of the silk of the oak worm as compared 

 with that of the common kind. In two specimens, one of the 

 Italian and the other of yamamai train silk, prepared in the 

 same establishment for dyeing in black by a mordant of iron, 

 it was found that the former took 1.82, and the latter only .81 

 of the oxide of iron. Hence it would seem that the yamamai 

 silk takes its mordant in an indifferent degree, and consequent- 

 ly is less adapted to receiving colors. 



The other experiments, of a somewhat similar character, 



