ALBUMENOID SUBSTANCES.

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long-continued boiling, and at the same time undergoes considerable modifi-cation. Coagulated albumen possesses the property of combining readilywith a great many colouring materials, such as fuchsine, aniline violet,purpuramide, and others, forming with them true organic lakes ; in this respedtalbumine is very similar to wool. According to Dr. P. Schutzenberger’sresearches, coagulated albumen can be converted into soluble albumen,and again coagulated by the application of heat: for this purpose coagulatedalbumen* is dissolved in as small a quantity as possible of a weak solutionof caustic potassa. The solution of albuminate of potassa thus obtained(free from other salts) is treated with an excess of acetic acid, the pre-cipitate being submitted to dialysis, and the water frequently changed until itis no longer acid. The water of the interior of the dialyser will, on examina-tion, be found to exhibit a slight opalescence; and under the influence ofheat, as well as on addition of nitric and other mineral acids, there appears inthis fluid a heavy, flocculent precipitate. This precipitate occurs also onadding the solution either of a neutral salt or a very small quantity of analkali. But fresh albumen when slightly acidified with acetic acid and sub-jected to dialysis without previous coagulation, exhibit also these phenomena.

The sources of albumen available industrially are the eggs of birds,especially those of the domesticated Gallincicece , and the serum of blood. Itis a matter of regret that no substitute has been found for albumen, becausethe number of eggs withdrawn from the food market for industrial purposes,greatly increases the price of this very nutritive commodity.

The albumen employed in printing bears a double utility, serving as avehicle for the colour, and adting at the same time as a varnish. Whensuperfluous albumen colours are washed off after steaming, none of the albumenis removed, but remains as an integral part of the pigment. This occurs in thecase of the so-called pigment colours, but in the fixing upon cotton of coloursderived from aniline the albumen is in effedt a true mordant, for having a greataffinity for aniline its adtion is similar to that of alumina or iron. Pigmentcolours are fixed upon the cloth merely by the coagulation of the albumen,which does not enter into combination with the colour, but with the cottonfibre.

Albumen as white of egg is met with in commerce in the dry state, havingbeen submitted to a temperature of 30° to 35 0 C. upon zinc trays, slightlygreased with olive oil to prevent adherence of the albumen to the metal.Eighty-four dozen eggs yield on average 6 litres (1*2 galls.) of white in fluidstate, and 4 litres (0*88 gall.) of yolk. After drying 14 per cent of commercialalbumen is obtained. The yolk finds many applications, as in the dressingof wash-leather, &c. The albumen obtained from blood has the disadvantageof being dark in colour, and is inapplicable except in few instances.

No satisfactory substitute for albumen has yet been discovered; in Germanyglue is sometimes employed, the printed cloth being passed through a solutionof alum or an aluminous salt to fix the colour; but neither as to fastnessnor brightness of colour can this method be commended. Shellac dissolvedin borax, india-rubber dissolved in naphtha, and many other solutions havefailed. Drying oils have been used as vehicles for the pigment, but aredifficult of application; yet were the investigations of Professsor G. J. Mulder

* Ihe albumen employed by Dr. Schiitzenberger was obtained by Lieberkuhn’s process.