On Recent Scientific Discoveries as Applied to Arts and Manufactures. Of Colour obtained from Coal Tar Products.

Journal of the Society of Arts 274, 19.2.1858
By Mr. Crace Calvert.

Eleventh Ordinary meeting.
Wednesday, Feb. 17, 1858.
The Eleventh Ordinary Meeting of the One Hundred and Fourth Session, was held on Wednesday, the 17th inst., William Odling, Esq., M.D., in the chair.
The following Candidates were balloted for and duly elected members of the Society: -
Abernethy, James
Cawley, Charles Edward
Figgings, James, jun.
Fleming, Thomas
Howard, James
Ripley, Henry William
Spencer, John Frederick.

The Paper read was:-
On Recent Scientific Discoveries as Applied to Arts and Manufactures.

By Mr. Crace Calvert.

Of Colour obtained from Coal Tar Products.

When, in November 1854, I had the honour to read before this society a paper on the products obtained from coal, I stated that ere long, besides carbo-azotic acid, some valuable dyeing substances would be prepared from this mineral. This expectation has been fulfilled. Messrs. W. Perkins and A. H. Church have obtained several blue colouring substances from the alkaloids of coal tar, and one from naphtaline, named by them Nitroso-phenyline and Nitroso-naphthyline, &c.

Mr. Perkins has lately taken a patent for the commercial application of some of these beautiful purple blue colours, which he has succeeded in fixing on silk, a sample of which I have the pleasure to lay before you. This fine colour, which rivals the delicate and admired colour of orchil, has this great advantage over it, that it is not destroyed by light; Mr. Perkins has, therefore, solved one of the problems of a fast colour similar to the fugitive one of orchil. Mr. Perkins's process consists in dissolving in water the sulphates of aniline, of cuminine, and of toluidine, and adding a quantity of bicromate of potash sufficient 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 napththa, and then dissolved in methylated spirits. This solution, with the addition of a little tartaric or oxalic acid, forms the dyeing liquor of Mr. Perkins.

Mr. Charles Lowe and myself have lately been fortunate enough to obtain from coal tar, products having a most extraordinary dyeing power, and yielding colours nearly as beautiful as safflower pinks and cochineal crimsons; and what increases the interest of this coal tar product is, that by one process we have discovered, we can obtain with it, on a piece of calico mordanted for madder colours, all the various colours and shades given by this valuable root - violet, purple, chocolate, pink, and red. The only thing which has prevented us from introducing into the market the crown red inodorous paper which we prepare, has beem, that it is as yet too expensive to compete with this extraordinary colour-giving root, but we intend pursuing our researches in the hope of employeing it as a substitute for safflower or cochineal, two colouring matters, the price of which is sufficiently high to induce us to continue our investigations. We may add, that our imitation of safflower colour stands soap and light, whilst safflower colours do not.

I shall now draw the attention of the meeting to the preparation, dyeing, and printing of a magnificent crimson colour, called murexide, obtained from guano, as substance which, until lately, has been entirely imported for agricultural purposes. The interesting application of this colour to calico-printing has been, like many valuable chemical discoveries, progressive, and has only been brought to successful commercial application by successive discoveries, made by various persons.

Prout was the first chemist to remark that if the foeces of serpents were heated with nitric acid, and a little ammonia added, a beautiful purple colour was produced. He named it purpurate of ammonia. This substance, when dry, has the apprearance of a dark-red powder, soluble in water, to which it comminicates a magnificent red colour. This solution not only gives a precipitate with metallic salts, but when evaporated yields beautiful crystals, having the iridescent apprearance of the wings of cantharides.

This discovery has also been useful to medical men, by enabling them to distinguish the uric acid calculi.

Messrs. Liebig and Wöhler had also investigated the subject, and succeeded in obtaining from the uric acid contained in the foeces of serpents this substance, which they called murexide, and a new class of organic substances, the knowledge of which has much facilitated the application of murexide to dyeing and printing. Mr. Saac was the first to apply the products of uric acid to the dyeing of fabrics; his process consisted in dipping woollen fabrics, prepared with a salt of tin, into a weak solution of alloxan, a product discovered by Liebig and Wöhler, in heating urea with nitric acid. The fabric so prepared was dried, and when submitted to heat a fine crimson was generated, the intensity of which increased by the fumes of ammonia. But owing to difficulty of obtaining a colour of uniform shade, Mr. Saac's process required improvements, and these have been effected by Mr. Schlumberger.

The process followed by Messrs. Saac and Schlumberger, could not be applied to silk or cotton fabrics. The method of dyeing silk with murexide was discovered by M. de Pouilly, who adopted the following processes, viz., dipping the silk in a concentrated solution of bichloride of mercury mixed with murexide, aqueezing the silk well and hanging it in the air, when a magnificent crimson insoluble compound is fixed on the silk. This effect is produced from the fact that when solutions of bichloride of mercury and murexide are mixed together, an insoluble compound is only formed after the lapse of an hour or two.

The process of dyeing cotton is due to Messrs. Lauth and Schlumberger, and consists in producing on cotton a purpurate of lead by mordanting with nitrate of lead, passing into an alkali, and then dyeing in a solution of murexide; in order to give full brilliancy to the colour, it is lastly passed through a weak solution of bichloride of mercury. This process was further improved by Messrs. Dolfus, Meig and Co., in France, and Mr. Lightfoot, in Lancashire, by printing murexide with an excess of nitrate of lead, and subjecting the cloth so printed to the action of ammoniacal fumes, or passing it through a solution of caustic soda mixed with sal ammoniac. In order to render this substance more generally usedful, it remained to find a method for obtaining fast colours with it on mixed fabrics, such as mousseline de laine, and this has also been effected by Mr. Schlumberger. The cloth is first prepared by uniting binoxide of tin with the wool. This object is attained by using a salt known to calico printers as pink salt, the double chloride of ammonium and tin, and then printing on the prepared fabric the following mixture: -
1 part of murexide.
6 parts of nitrate of lead.
2 parts of nitrate of soda.

The pieces are then allowed to age for two or three days, when, to fix the purpurate of lead on the cotton, and the purpurate of ammonia on the wool, it is necessary to pass the cloth into a bath of bichloride of mercury, composed as follows: -
Water 100 gallons
Bichloride of Mercury 6 pounds.
Acetate of Soda 12 pounds.
Acetic Acid 2 quarts.

Until recently, all the green colours produced on fabrics were the results of blue and yellow mixed together; but of late public attention has been drawn to a green matter discovered by the Chinese, and fixed by them on cotton. It has been ascertained that they prepare it, by a long and tedious process, from two plants called Pa-bi-lo-za (Rhamnus chlorophorus) and Hom-bi-lo-za (Rhamnus utilis), and sell it in small square cakes, under the name of Luh-kaou or Luh-chao. The first commercial importation of this colour, new to us, is quite recent, as the first public sale of it in England  took place a week ago, at the quarterly indigo sales, under the name of China green indigo. No sooner had a foreign green substance been brought to our notice, than in Europe we had succeede in obtaining also green dyeing substance from the plants which surround us, and Mr. Schlumberger gas been fortunate enough to fix on woollen fabrics the green chlorophylle, or colouring matter of leaves and grass. This discovery will, in time, prove of great service to dyers and calico printers. Mr. Schlumberger's process consists in boiling 60 lbs. of grass with 25 gallons of water. This operation is repeated, and the grass then treated with 25 gallons of soda lye, with addition of 2 to 4 lbs. of mercer's dung substitute (phosphate of soda and lime). Boil half [---] then add excess of hydochloric acid; a  [---] precipitate falls, which is separated by filtration.  [---] is dissolved in very dilute soda lye, adding a little of the substitute and the silk or wool to be dyed is dipped in until the desired shade is obtained. Stannate of Soda is the only mordant which gives us beneficial results.

M. Pelouze has rendered lately a great service for Turkey red dyers by enabling them to use any oil, instead of only Gallipoli oil, and of special quality.  [---] Pelouze has discovered that the difference there was betwixt a Gallipoli oil, which could be employed with advantage to produce a Turkey red on cotton, and  [---]  which could not, was, that the first contained a  [---]  proportion of free fatty acids, whilst the latter was nearly neutral. This led Mr. Pelouze first to prepare, artificially, oils of good quality for Turkey red by  [--- mixing?] oleic acid with neutral oils; and, secondly, to the interesting scientific observation that oils were  [---]  of undergoing a spontaneous fermentation as  [---]  saccharine juices, or other organic fluids. Thus, immediately the neutral fatty matters in the cells of fruit roots are brought in contact with the ferment which vegetable substances contain, by breaking the cells  [---in?] which the fatty matters are deposited, the oil enters  [---]  fermentation, and the fatty acids are liberated from  [---] glycerine with which they had been combined.  [---] discovery gives us an insight into the acidity of some  [---]  and the rancidness of others.

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