Technical Chemistry. | 423 
_ . mixture it separates as a reddish-brown precipitate. This, when washe 
with water on a filter and then dried, is dissolved in poe sere and 
evaporated to dryness on the water-bath. Thus prepared, it is a crystal- 
’ line, dark-colored substance, ha aving a procninlntuaitie seaweed It is 
soluble in ae and also in benzole, forming orange-red solutions. 
When acids are added to an alcoholic solution of nitroso- -naphthaline, it 
immediately assumes a most beautiful violet color, as fine as any aniline 
purple. Alkalies restore it to its original color. Silk may be dyed a 
beautiful purple shade with this substance, provided a certain quantity of 
hydrochloric acid, or sulphuric acid, be present. But what is most unfor- 
tunate is, that wher the silk thus dyed i is rinsed in water, the color imme- 
diately passes back to that of the pure nitroso-naphthaline, and also that 
the amount of acid required to keep up the purple shade, if left in the 
silk, rots itin a few days. Could this purple be fixed, nitroso-naphthaline 
would be a cheap and most useful dye ave endeavored to produce 
the sulpho-acid of nitroso-naphthaline, thinking that if such a compound 
could be obtained, it would possess a purple color because it would be an 
acid itself. But, although sulphuric acid does dissolve it, forming a blue 
solution, yet no combination takes place. I also endeavored to produce 
this desired result by treating sulpho-naphthalamic acid with nitrous acid, 
but obtained only — the acid of the sulpho-naphthala- 
mic acid eases: id ows separ 
hthamei 
duced blue precipitates, afterwards becoming aaa when smanae in con- 
tact with perchlorid or iron, terchlorid of gold, nitrate of va. and other 
oxydizing agents, is product of oxydation, he terms naphthamein. 
ae a residue of sleartial behind. It is sscletae4 in 
nates, sparingly soluble in alcohol, but more soluble in ether. It forms a 
blue solution with concentrated sulphuric acid, pe is reprecipitated fi rom 
it by water. It dissolves in concentrated acetic acid with a purple color, 
and is not precipitated from this solution by means of water. Silk and 
cotton may be dyed with it, but the color of this compound is so inferior 
4s to render it useless as a d ein 
Tar Red.—This coloring si discovered by Mr. Clift, of Man- 
chester, in 1853. It is obtained by exposing a mixture of the more yola- 
te * gr of the basic oils of coal-tar and hypochlorite of lime to the 
or about three weeks. Of the pure coloring matter I know nothing, 
sep that, with tannin, it forms an insoluble, or difficultly-soluble, ae 
With different mordants, it yields different ~rae seem 
probable that this coloring matter is derived from pyrro 
