436

DYEING AND CALICO PRINTING.

alcohol; the solution is precipitated with lime, and the lime lake thus producedis washed, and next decomposed by hydrochloric acid ; the acid solution isshaken up with ether, which takes up the green pigment. On evaporating theether the pure chlorophyl is left. The chlorophyl thus obtained is a deepgreen powder, unadted upon by exposure to air, not decomposed at 200°, andnot fusible at that temperature; insoluble in water, but soluble in alcohol,ether, acids, and alkalies : hydrate of alumina combines with this pigment,and withdraws it readily from its alcoholic solution provided it be first properlydiluted with water.

Nascent hydrogen reduces and decolourises chlorophyl, which, according toM. Verdeil, contains a large quantity of iron in a peculiar state of organiccombination analogous to the state iron is found in the haematin (red colouringmatter of blood).

According to Dr. G. J. Mulder, chlorophyl should contain nitrogen, but it ispresumable that the chlorophyl he prepared from grass was not sufficientlypurified, and therefore contained some protein compound. When an alcoholicsolution of chlorophyl is first diluted with water, and next treated with gela-tinous alumina, there is formed a deep green lake, while the supernatantliquid becomes yellow. This experiment has suggested to M. Fremy the ideaabove alluded to, and the following plan of separating the supposed pigments:—First, a saturated solution of hydrochloric acid in ether is made, by mixing in aglass stoppered bottle 2 parts of ether and 1 part of hydrochloric acid, slightlydiluted with water ; the acid is made to saturate the ether by strongly shakingthe bottle containing the mixture : on the other hand, the chlorophyl is treatedwith an alkali, whereby it is converted into a beautiful yellow body, soluble inalcohol, ether, sulphide of carbon, and capable of forming with hydrate ofalumina a yellow lake, which, on being decomposed by means of an acid, givesup its pigmentary matter to any of the solvents just named.

When the yellow pigment just mentioned is treated with the mixture ofhydrochloric acid and ether the latter fluid becomes purely yellow, while thelower layer of hydrochloric acid assumes a beautifully blue tint. The expla-nation of this phenomenon is given by M. Fremy in the following terms:—Chlorophyl, he says, is a mixture of a blue and a yellow pigment, the blue ofwhich is temporarily bleached by alkalies, and the yellow pigment—which theyproduce from the originally green-coloured substance—is a mixture of theprimitive yellow and the colourless product formed by the adtion of the alkaliesupon the cyanin. When, therefore, the yellow matter is treated with etherand hydrochloric acid, the original yellow pigment of the chlorophyl is dis-solved in the ether, and the cyanin, being restored to its colour by the acid,becomes dissolved in the latter, forming a blue solution. This experimentmay be readily made, either with chlorophyl or with previously dried greenleaves.

The name of phylloxanthin is given by M. Fremy to the supposed originalyellow constituent of chlorophyl, while he calls the yellow substance resultingfrom the temporary alteration of the blue principle (phyllocyanin) containedin chlorophyl, phylloxanthein.

The regeneration of phyllocyanin by acids does not require the adtion ofair. When plants are reared in the dark, or at least nearly so, diredt sunlightbeing excluded, they contain phylloxanthin and phylloxanthein, and by the