176
DYEING AND CALICO PRINTING.
Luxer ascertains the value of commercial anilines by estimating the amountof red colour which they respectively yield. Five grammes of the aniline inquestion and 5 grammes of syrupy arsenic acid, of sp. gr. 2-059, are beated to150° for several hours, in the oil-bath, until the formation of a reddish-brownsubstance, with a greenish reflection, which on cooling becomes a hard, brittlemass. This is exhausted with boiling water, and made up to the bulk of1 litre : 50 c.c. of this solution are taken and diluted with water to t litre, andin this fluid 6 grms. of woollen yarn are dyed, and the resulting samples com-pared as to intensity and tone. This test is considered fallacious by manypractical men, as with such small quantities the regulation of the temperatureis very difficult. Thus a variable quantity of aniline may remain unaCted upon.It is necessary that the manufacturer should previously satisfy himself whatboiling-points of aniline, or of a mixture of aniline and toluidine, are bestadapted for his purpose. This having been done he will find the boiling-pointa valuable guide.
Reimann, to distinguish the so-called light from the heavy anilines,—or, ashe names them, kuphaniline and baraniline,—heats slowly a certain quantityof any sort of aniline oil, and notes the quantity which distils over at varioustemperatures, degree by degree. More simply, the quantities are noted whichdistil over during a rise of 5 degrees. The quantities of distilled oil may bemeasured by receiving them in a graduated cylinder.
He puts 100 c.c. of kuphaniline in a glass retort, placed in an oil-bath heatedby a lamp. The tube of the retort is joined to a Liebig’s condenser, at theextremity of which a graduated cylinder is placed to receive and measure whatdistils over. The condenser is supplied with water in the usual manner; athermometer is placed in the neck of the retort, and heat applied. Up to180 0 C., 8£ c.c. passed over; from 180 0 to 185°, 54 c.c.; and from 185° to 190°,34 c.c.; so that, say, 3^ remained in the retort. Other samples of light anilineyield numbers, not indeed identical, but similar.
Heavy anilines treated in the same manner allow only 3^ c.c. to pass overup to igo° C. From igo°to 195°, 8 c.c. distil over; up to 200° C., 18; to205° C., 39; from 205° to 210°, ig ; and from 210° to 215 0 , 7 c.c.; 5$ remainingin the retort. All the anilines of commerce are mixtures of light and heavyaniline in various proportions, and they distil over at intermediate tempera-tures, according to their composition. By distilling the following mixtures—
go per cent kuphaniline with 10 per cent baraniline
85
tt
15
80 '
tt
20
75
It
25
62i
tt
37 i
60
tt
40
5 °
It
5 °
37i
tt
621
25
tt
75
—and adding to the result the numbers given above, found by distilling purekuphaniline and baraniline, he has constru&ed the following table, where Kdenotes light and B heavy aniline :—