THE JOURNAL OF THE S0CI~'I'Y OF DYERS AND COLOURISTS. IFeb. 25,IW. - - 24

and residues are available. Seeing that orchil and cudbear are soluble in ammonia, it occurred to me that this reagent might be applied for the qnantita- tive determinstion of basic magenta in an impure sam le. I a plied this test in the following manner :

TEe orchiPliquor is first filtered to remove any insoluble vegetable matter which i t may possibly contain. The filtrate is then evaporated to dryness, and ground as i n the previous test. I n the case of cudbear or orchil aste it would, of course, be neces- sary in the first prace to di est with hot water, and then filter. A small weigfed portion of the dried residue is then digested with strong ammonia, filtered, and washed with ammonia until all the orchil iswashed through, and the filtrateis colourless. The basicmagenta will remain i n the filter, and after being dried in a steam bath may be separated from the filter and weighed. If preferred, of course, a counterpoise filter may be used. I have found this method to give tolerably accurate results.

-- --- NEW COLOURING MATTERS.

COMMUNICATION FROM EDMUND KNECBT, PH.D.

Turtrrtzin.-This colonring matter is of great theoretical interest as being the first commercial re resentative of a totally new series of coal-tai cofours. According to the patent specification: tartrazin is obtained by heating together in solution bioxytartaric acid and phenylhydrazine-sulphonic acid for $-1 hr. to SOoc. The colouring matter if precipitated on cooling and is filtered, pressed and dried. Its composition has not yet been determined but it seems probable that i t is a mixed azo-compound and that its mode of formation is closely allied tc that of alpha-oxyazonaphthalene from alpha-naphtho quinon and phenylhydrazine.

Tartrazin forms a bright oran e yellow powder which dissolves easily in water, wit! yellow colour The aqueous solution is not perceptibly changed b j the addition of dilute sulphuric acid, but caustic soda solution turns it somewhat darker. By the addition 01 alcohol to the concentrated aqueous solution, it is pre- cipitated in a crystalline form. Concentratedsulphuric acid dissolves it with a yellow colour. With stannous chloride or stannic chloride the aqueous solution yields yellow preci itates soluble in oxalic acid.

Tartrazin may \e dyed on wool or silk in acid baths, one per cent of the colouring matter being sufficient to produce a full yellow. The shade i s somewhat similar to that obtained with na hthol. yellow S. Wool dyed with tartrazin and b o i i d in a solution of soap is turned somewhat darker, and does not give up its colour unless the soap is stronglj alkaline, and used in an absurd degree of concentra. tion. Wool dyed with tartrazin and milled togethei with white yarn does not bleed in the slightest degree Both of these roperties would make the colouring matter applica%le to goods which have to stand milling (in place of flavin or Persian berries). Ac. cording to Dr. von Perger (Romen's JownaZ),tartrazin mixed with dextrin and stannous chloride, printed on wool and steamed, does not give good results, on account of the reducing action of the stannous chloride; but if the latter is replaced by stannic chloride, shades are obtained which in urity and brilliancy are almost equal to those proluced with uranin. I have hitherto not had an opportunity of testing the fastness of this colouring matter to light.

Nrr ~htiiylnniine r e d , whichhas recently been brought into t i e market, is one of the class of fast reds, and belongs therefore t o the azo-dyes. It is obtained by the actioQ of diazonaphthionic acid on the soda salts

of naphtholsulphonic acids. Naphthylamine red forms a dark brown-red powder easily soluble in water. I n concentrated sul huric acid it dissolves with a characteristic vioyet-blue colour. It is applied in dyeing like the other azo-dyes, and yields bluish shades of red on wool.

- - ~~ - .~ _ _

aournais. __yvyy^^_w____U____^__Y_YYYUT^I

111,-NORDANTS, On the Soldility of Antimony Oxide in Alkaline Solu-

tions of Glycerin ; and on a New Mordant for Cotton. H. Kohler.

GLYCERIN has the pro ert of dissolving the hydrates of the alkali metals, of t i e arkaline earths, and of certain metallic oxides, forming compounds which are probably closely allied to the alcoholates. The hydrates of the alkalies and alkaline earths dissolve at once ; but of tho heavy metals only lead possesses this property, while a number of others, such as the oxides of iron, manganese, copper, and bismuth, will only dissolve in alkaline solu- tions of glycerin.

According to the results of experinients carried out by the author, antimony oxide also belongs to this class of oxides. It will not dissolve in pure glycerin, but if the glycerin is made alkaline, its solubility is very consider- able. Systematic experiments were carried out in order to find the most suitable conditions with respect to alka- linity (causlic soda was used), time of action, and tem- perature in preparing solutions of antimony oxide for use, and the following is the resume' of the results :- The solubility of antimony oxide in gljcerin increases rapidly with increasing alkalinity, until the molecular proportion of glycerin to caustic soda is a s 1 : 1. Beyond this point the solubility, with increasing ninounts of caustic soda, docs indeed increase, but not nearly so rapidly. The author makes a su nestion that the reac- tion might be expressed in the folkwing eqnation :-

Dingl. Polyt. Jour., Vol. 258, No. 12.

CHZOH CH20Na UH I O H + N a O H + Y b 2 0 ~ = ~ H 0 . S h 0 + 2 H 2 0

CHpOH I I C: H1OSbO.

With respect to time of action and temperature, the best results mem to be obtained by heating the sub- stances on the zontev-bath for one houi:

Experiments were also made with caustic potash and ammonia, but it was fonnd that the former does not give nearly such good results as caustic soda, while ammonia does not act a t all.

The solutions obtained in the manner described are always strongly alkaline, and can only be neutralise4 with acids up to a certain point, beyond whicli the anti- mony oxide separates out as thick, curdy recipitate, soluble in excess of hydrochloric acid. From tks solution the antimony is again thrown down by excess of water ; glycerin does not, therefore, prevent the precipitation like tartaric acid does. If the alkaline solution is ex- posed to the air it rapidly becomes turbid, and a white rrystalline precipitate, consisting of Na,Sb,O,, is formed. On the salts of the heavy metals the solution acts like frec alkali, precipitating the hydrates alonv with anti- mony oxide. The author suggests that th:s property might be made use of for the preparation of certain colour lakes.

Great care xlionld be taken in p r e y i n g the mordant to see that the antimony oxide IS ree from antimony sulphide, whicli would become fixed to the fibre by the tannin, and, owing to its redcolonr, would tend in man instnnces to produce dull shades. The presence of s u l phide in the mordant can easily be detected by saturatin a smallqnantityin a test-tube withhydrochloric acid,unt$ all the antimonyoxide is dissolved,and allowing the liquid