ANILINE REDS.

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Magenta can also be dissolved in certain saline liquids, such as solutionsof bicarbonate of soda, carbonate and bicarbonate of ammonia, and borax.These solutions dye redder shades than magenta dissolved in alcohol, glycerine,or water—an effedt which can be, to some extent, also produced by adding alittle white soap to the dye-bath. On the other hand, if it be desired to pro-duce a more blue tone, a little tartaric or sulphuric-acid is added.

In cotton dyeing a mordant is needed to cause the magenta to be firmlyfixed upon the fibre. The seledtion is governed by the circumstances of the case.

If the article to be dyed consists entirely of cotton, whether in the state ofyarn, or of a woven tissue, it may be prepared as for Turkey-red, or workedfor a couple of hours in a decodtion of commercial tannin, of good nut-galls,or of pale myrobalans,* or any other substance rich in tannin, but free fromcolouring matters. The cotton goods are then taken out of the tannin liquor,allowed to drain for a short time, and then worked in a weak solution ofstannate of soda for about an hour. Next they are passed through waterslightly acidulated with sulphuric acid, or with alum. They are then rinsedin pure water and worked in the magenta solution at ordinary temperaturesto the shade required. Some dyers vary the order and apply the stannateof soda first and the solution of tannin afterwards.

Another process is to work the cotton yarn in a solution of the subacetateof lead, and afterwards in a solution of soap.

In piece-dyeing, where the weft is wool or worsted, and the warp cotton, adifferent procedure is necessary. The pieces are winced first in an infusionof gall-nuts or other similar material, and then in a solution of tin-crystals.The pieces are then rinsed in water and transferred to the colour-bath. Somedyers omit the tannin-bath lest it soil the wool, and others use instead of thetin-crystals a peculiar nitro-muriate of tin, which will be subsequentlydescribed as “ Aniline Mordants.”

In printing, magenta is applied to calico with albumen, and thickened withstarch or gum. “ Ladtarine ” (caseine) may also be used instead of albumenwhen no additional thickening is needed. In either case the goods afterprinting are steamed from thirty to sixty minutes.

Another method, invented by Schultz, is to mix J litre of acetate of aluminaat io° of Baume’s hydrometer with 20 grms. arsenite of soda to every 4 grms.of magenta. This mixture is thickened with starch which has been boiledseparately. The quantity of starch is increased the lighter the shaderequired. In printing this composition is mixed with the amount of colourrequired, and the goods are afterwards steamed.

The red in the accompanying pattern is magenta, fixed as above mentioned.The violet is Hofmann’s (see below); the green, chrome-green, both fixed inthe same manner as the magenta. The black is a so-called chrome-black, amixture of logwood and bark-liquor, with chlorate of potash and acetate ofchromium for mordant, thickened with starch and gum, and steamed.

Examination of Magentas.

The simplest method of testing a commercial sample of magenta, both forintensity and for purity of tone, is to dissolve a known weight in boiling

* Contrary to an old prejudice,myrobalans are preferable to the best sumac, as they containan oil which assists in the fixation of aniline colours.