Page:Proceedings of the Royal Society of London Vol 1.djvu/237

Rh to the brown precipitate obtained, by nitric acid, from the solution of guaiacum in alcohol, and possessed the properties of a resin in greater perfection than guaiacum itself. If successive portions of nitric acid be added to the above-mentioned residuum, or if a large quantity of that acid is employed so as to form a complete solution, a product may be obtained, by evaporation, which is equally soluble in water and in alcohol; both which solutions have an astringent bitter taste.

Guaiacum is soluble in the pure and in the carbonated alkalies. The precipitates formed from these solutions, by dilute sulphuric acid and by muriatic acid, were of a ﬂesh colour, and approached to the nature of extract; being less acted upon by sulphuric ether, but more soluble in boiling water than guaiacum.

Mr. Brande now proceeds to the analysis, by distillation. of the substance here treated of. By this method he obtained, from 100 grains, the following products :— The coal, on incineration, yielded four grains of lime, but no alkali could be discovered.

From the foregoing experiments it appears, that although guaiacum possesses many of the properties common to resins, it differs from them in the following circumstances.

1. By affording a portion of vegetable extract.

2. By the alterations which take place in it when submitted to the action of bodies which readily communicate oxygen, such as ni- tric and oxymuriatic acids, and by the rapidity with which it is dis- solved in the former.

3. By being capable of being converted into a more perfect resin, in which it resembles the green resin that constitutes the colouring matter of leaves.

4. By yielding oxalic acid.

5. By the quantity of charcoal and lime obtained from it by dis- tillation.

These circumstances, the author says, shows that guaiacum diﬁers not only from the substances denominated resins, but also that it dilfers from those which are called halsams, gum-resins, gums, and extracts; and he thinks we may, for the present, consider guaiacum as composed of a resin. modiﬁed by the vegetable extractive prin- ciple, so that it may perhaps, without impropriety, be deﬁned by the term Extracto—resin.

In a postscript Mr. Brande observes, that the action of oxygen on some othcr resinous bodies is very remarkable. By digesting mastic