Part 9 (1/1)

(_c_) Aniline oil for safranine

(_d_) _Liquid toluidine

From the first of these, which is almost pure aniline, aniline black is derived, and a nuanic compounds which are further used for the production of dyes The hydrochloride of aniline is important and is known commercially as ”aniline salt”

The distillation and rectification of aniline oil is practised on a similar principle to the fractional distillation which we have noticed as being used for the distillation of the naphthas First, light aniline oils pass over, followed by others, and finally by the heavy oils, or ”aniline-tailings” It is a ed in colour manufacture to apply that quality oil which is best for the production of the colour required This is not always an easy ence of opinion and in practice on these points

The so-called aniline colours are not all derived fro in some cases derived from other coal-tar products, such as benzene and toluene, phenol, naphthalene, and anthracene, and it is reh the earlier dyes were produced frohter and more easily distilled products of coal-tar, yet now some of the heaviest and ht under requisition for colouring arded as fit only to be used as lubricants or to be regarded as waste

It is scarcely necessary or advisable in a work of this kind to pursue the many chemical reactions, which, from the various acids and bases, result ultiradations of colour which are to be seen in dress and other fabrics Many of them, beautiful in the extreme, are the outcome of much careful and well-planned study, and to print here the coes taking place in compounds of complex molecules, or to mention even the names of these many-syllabled compounds, would be to destroy the purpose of this little book The Rosanilines, the Indulines, and Safranines; the Oxazines, the Thionines: the Phenol and Azo dyes are all substances which are of greater interest to the chemical students and to the colour manufacturer than to the ordinary reader Many of the names of the bases of various dyes are unknown outside the cheh each and all have complicated; reactions of their own In the reds are rosanilines, toluidine xylidine, &c; in the blues--phenyl-rosanilines, diphenylamine, toluidine, aldehyde, &c; violets--rosaniline, reens--iodine, aniline, leucaniline, chrysotoluidine, aldehyde, toluidine, e--leucaniline, phenylamine, &c; browns--chrysotoluidine, &c; blacks--aniline, toluidine, &c

To take the rosanilines as an instance of the rest

Aniline red, enta, azaleine, rubine, solferino, fuchsine, chryaline, roseine, erythrobenzine, and others, are colouring roup which are salts of rosaniline, and which are all recognised in commerce

The base rosaniline is known chemically by the for a enta aniline, toluidine, and pseudotoluidine, with arsenic acid and other oxidising agents It is important that water should be used in such quantities as to prevent the solution of arsenic acid fro Unless carefully crystallised rosaniline will contain a slight proportion of the arseniate, and when articles of clothing are dyed with the salt, it is likely to produce an inflao there was a great outcry against hose and other articles dyed with aniline dyes, owing to the bad effects which were produced, and this has no doubt proved very prejudicial to aniline dyes as a whole

Again, the base known as mauve, or mauveine, has a composition shown by the formula C_{27}H_{24}N_{4} It is produced fro it with a cold saturated solution of bi+chro the mixture to stand for ten or twelve hours A blue-black precipitate is then for a process of purification, is dissolved in alcohol and evaporated to dryness Apowder is then obtained, which constitutes this all-important base Mauve forms with acids a series of well-defined salts and is capable of expelling ammonia from its combinations Mauve was the first aniline dye which was produced on a large scale, this being accomplished by Perkin in 1856

The substance known as carbolic acid is so useful a product of a piece of coal that a description of the method of its production must necessarily have a place here It is one of the ents hich we are acquainted, and has strong anaesthetic qualities Some useful dyes are also obtained from it It is obtained in quantities froht oils being its immediate source The tar oil is mixed with a solution of caustic soda, and the itated This results in the caustic soda dissolving out the carbolic acid, whilst the undissolved oils collect upon the surface, allowing the alkaline solution to be drawn from beneath The soda in the solution is then neutralised by the addition of a suitable quantity of sulphuric acid, and the salt so formed sinks while the carbolic acid rises to the surface

Purification of the product is afterwards carried out by a process of fractional distillation There are various othercarbolic acid

Carbolic acid is known chemically as C_{6}H_{5}(HO) When pure it appears as colourless needle-like crystals, and is exceedingly poisonous It has been used withthe course of disease, such as cholera and cattle plague It is of a very volatile nature, and its efficacy lies in its power of destroying germs as they float in the atmosphere Modern science tells us that all diseases have their origin in certain germs which are everywhere present and which seek only a suitable _nidus_ in which to propagate and flourish Unlike ases or odours; unlike disinfectants which prevent the spread of infection, carbolic acid strikes at the very root and origin of disease by oxidising and consuerms which breed it So powerful is it that one part in five thousand parts of flour paste, blood, &c, will for months prevent fermentation and putrefaction, whilst a little of its vapour in the atmosphere will preserve h it has, in certain ireeable odour, this is never such as to be in any way harmful, whilst on the other hand it is said to act as a tonic to those connected with its preparation and use

The new artificial colouring ht into the market, testify to the fact that, even with the many beautiful tints and hues which have been discovered, finality and perfection have not yet been reached A good deal of popular prejudice has arisen against certain aniline dyes on account of their inferiority to many of the old dye-stuffs in respect to their fastness, but in recent years the e of looseness of dye, has entirely ceased, whilst others have been introduced which are quite as fast, and sometimes even faster than the natural dyes

It is convenient to express the constituents of coal-tar, and the distillates of those constituents, in the forical chart, and thus, by way of conclusion, summarise the results which we have noticed