Technical Chemistry. : 421 
continued at intervals until three-fourths as much potash has been a 
18 equivalent to the iodine in the iodid of amyle used. The fluid may, 
after a quarter of an hour’s ebullition, be filtered to separate the resinous 
color. The product is a gorgeous blue with scarcely any shade of red. 
On adding the other fourth of potash to the filtrate while gently boiling, 
a black mass will be precipitated containing all the red, which would 
otherwise have been mixed with the blue. is mass dissolves readily 
in aleohol, yielding a rich purple solution, containing, however, an excess 
ofred. The alcoholic solution, on filtration, leaves on a filter a dark mass 
soluble in benzole, and as sometimes prepared, affording a brilliant eme- 
rald-green solution of great beauty. It is not always easy to obtain this 
n color,” 
88 having a brilliant emerald-green color of great beauty. I have ob- 
epee h 
d 
chinoline blue, it changes into green; but whether this is the green spo- 
én of by Williams, I am unable to state. : : 
Naphthaline Colors—The beautiful hydrocarbon, naphthaline, _— 
hlororynaphthalic a cid s.- 
Were discovered by Laurent. They are produced by digesting their chlo- 
mely, the chlorid of chloroxynaphthyle and the chlorid of pe 
ti { repare them. 
They have the formula C,(H,Cl)O,, and C,,(HCI,)O,, respectively. 
They are regarded with great interest, as being very closely allied with 
alizarine, the coloring matter of madder; in fact they are viewed as 
C,,H,0 tha ‘ ‘ 3 4 ‘ ‘ 
18 theory, that the formula of alizarine itself is still a disputed point. 
Chloroxynaphthalic acid is of a yellow color. It is insoluble in water, 
