Gluten is greyish coloured, and extensible whilst fresh and moist, like caoutchouc. It turns blue when mixed with guaiacum resin.
Gluten Bread. Prep. 1. From wheat flour which has been deprived of about 2-3rds of its starch by washing it with water.
2. From gluten flour. Recommended in diabetes.
Gluten Choc′olate. (Gentile’s.) A mixture of cocoa and gluten flour. As a nutritious and appropriate food in diabetes.
Gluten Flour. Prep. 1. From the waste gluten of the starch works, washed, dried, and ground.
2. (Gentile’s.) From the last, mixed with about an equal weight of wheat flour.
GLYC′ERIN. C3H3O3. Syn. Glycerin, Hydrated oxide of glyceryl; GLYCERINUM, L. A sweet syrupy liquid formed during the saponification of oils and fats.
Prep. 1. Olive oil (or other suitable oil), protoxide of lead, and water are heated together until an insoluble soap of lead (lead plaster) is formed. The glycerin remains in the aqueous liquid. As this crude solution of glycerin is produced in great quantities in the manufacture of lead plaster, the operative chemist has only to purify it. This may be done as follows:—
The water and washings from lead plaster are mixed together, filtered, and submitted to the action of a stream of sulphuretted hydrogen to throw down the lead; the supernatant liquor is decanted from the precipitate, filtered, and evaporated to the consistence of a syrup in a water bath. To render it quite pure it is diluted with water, decoloured with a little animal charcoal, filtered, and again evaporated to the consistence of a thin syrup, after which it is further evaporated in vacuo, or over sulphuric acid, until it acquires the sp. gr. 1·265.
2. (M. Bruère-Perrin.) From the sweet liquor of the stearine works (a product of the process of lime-saponification). The quantity of lime present in the sample is first determined by means of oxalic acid, and the proportion of sulphuric acid necessary for its saturation at once calculated and added; the crude liquor is then concentrated in a tinned-copper vessel, evaporation being promoted by brisk agitation, until the sp. gr. sinks to 10° Baumé; it is next cooled and filtered, and accurately neutralised (if it is required) with carbonate of potassa, after which it is evaporated to the sp. gr. 24° Baumé; on cooling, it deposits gelatinous sulphate of potassa; the whole is now filtered, the deposit on the filter washed with a little very weak spirit and water, the filtrate and washings mixed together and evaporated, as before, with agitation, until the sp. gr. 28° Baumé, whilst hot (36° cold), is attained, when the whole is allowed to cool; the clear liquid is, lastly, decanted