Tannin is precipitated in the stomach as an inert tannate; gallic acid is to be preferred for this reason, and also for its pleasant taste and less irritating effect on the mucous membrane.
Mr. William Crookes has shown, that when a saturated solution of gallic acid is required in large quantities, that it is better to dissolve at once two ounces of gallic acid in six ounces of alcohol (60 deg.
Gallic acid, he feels assured, does not produce any notable effects in the process; but he thinks that the quality of the leather depends, in some degree, upon the quantity of extractive matter it may imbibe.
The vegetable principles that had been regarded as more usually present in astringent infusions, are tannin, gallic acid, and extractive matter.
In this case the liquor will appear in the course of a few weeks as if traversed with numerous crystalline colourless needles of gallic acid.
If a tannin infusion be largely diluted with hard water and a little iodine solution added, the pyrogallol tans yield either a purple-red or a dark blue colour, the former being a reaction of gallic acid.
The reaction is due to gallic acid or a similar grouping, and is, in the author's experience, the most satisfactory qualitative test for the group.
They yield no bloom or gallic acid, but have associated with this other characteristic substances.
To conclude this subject, I have only to add a few words on the gallic acid.
Common writing ink is a precipitate of sulphat of iron by gallic acid; the black colour is owing to the formation of gallat of iron, which being insoluble, remains suspended in the fluid.
Tannic Acid, which is equivalent in composition to a combination of Gallic Acid with a saccharine matter, is a valuable external Astringent.
Braconnot, that Tannic is a compound acid consisting of Gallic Acid in combination with the elements of grape-sugar.
And as the Tannic Acid loses weight by the decomposition, it follows that a dose of Gallic Acid produces a greater effect as a medicine than an equal amount of the other.
Tannic Acid, Gallic Acid, and Creosote are the three chief Vegetable Astringents.
In British pharmacy gall-nuts are used in the preparation of the two astringent ointments unguentum gallae and unguentum gallae cum opio, and of the tinctura gallae, and also as a source of tannin and of gallic acid (q.
Gallic acid is most readily obtained by boiling the tannin procured from oak-galls by means of alcohol and ether with weak solution of acids.
Gallic acid, however, does not coagulate albumen and therefore possesses no local astringent action.
Feist's preparation which were so great that the latter no longer could be considered a single glucoside of gallic acid.
Pour it on and off the plate to well permeate the film, then set the plate up to drain, and dry without washing off the gallic acid solution.
Let the plate dry; when perfectly dry, moisten the plate with distilled water, and pour over the following solution: Gallic acid 2 gr.
But, if required, the negative picture can be readily changed into a positive one, by converting the darkened silver into white metallic silver, by a mixture of protosulphate of iron and pyro-gallic acid.
The image is latent, until it is developed by pouring over the plate a mixture of pyro-gallic acid in distilled water, acetic acid, and nitrate of silver.
With regard to the sensitizing by nitrate of silver, the bringing out of the image under the action of gallic acid, and fixing the proof by hyposulphite of soda, I follow the usual methods, most frequently that of Mr. Le Gray.
I add only, if I have any dissolved, 1 or 2 grammes of camphorated spirits to 1 litre of the solution of gallic acid.
At the same time, it preserves the lights and the half-tones in a way that surprises me upon each new trial (I have not yet been able to obtain one clear proof by gallic acid, with the addition of nitrate of silver).
Now, make a solution of gallic acid in cold distilled water: the quantity dissolved is very small.
The paper is first iodized in the usual way; it is then washed over with a saturated solution ofgallic acid in distilled water and dried.
As soon as the picture appears, in about a minute, pour on a saturated solution of gallic acid abundantly, and keep it from pooling with the brush, using it with a very light hand.
The above list will hopefully provide you with a few useful examples demonstrating the appropriate usage of "gallic acid" in a variety of sentences. We hope that you will now be able to make sentences using this group of words.
