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Four years ago, F. Grace Calvert, an eminent English chemist, made the extraordinary statement before the Society of Arts that "ere long, some valuable dyeing substances would be prepared from coal." A few weeks ago he stood up before the same society in London, to demonstrate the truth of the above expression, by showing them a beautiful purpleish blue color, rivaling that of orchil, and having the great advantage over it of not being destroyed by light. These colors, for there are many of them, have been prepared from the alkalies of coal tar by Messr3. W. Perkins and A. H. Church, two rising discoverers, and have been called by them nitroso-phenyline and nitroso-naphthyline, c. The colors have been tried on silk, and found perfectly fast. Mr. Perkins' process is as follows :— He dissolves in water the sulphates of aniline, of cuminine, and of toluidine, and adds sufficient bichromate of potash to neutralize the sulphuric acid in these sulphates. The whole is left to stand for twelve hours, when a brown substance is precipitated, which is washed with coal tar naphtha, and then dissolved in methylated spirits. This solution, with the addition of a little tartaric oxalic acid, forms the dyeing liquor of Mr. Perkins. Messrs. Grace Calvert and Charles Lowe have prepared from coal tar products of a most extraordinary dyeing power, and yielding colors nearly as beautiful as safflower pinks and cochineal crimsons; and what enhances the value of the discovery is, that upon cloth colored with them, all the varieties of shades and colors given by madder are obtained—violet, purple, chocolate, pink, and red. These colors stand light and soap, which the originals, safflower colors, do not. The processes by which these wonders of chemical art are manufactured are not yet known; but we shall look carefully for them, and give them to our readers. Just imagine a crimson silk handkerchief dyed with a piece of coal!
