Two fluids, one of which is a solution of nitrate of silver in ammoniacal water, and the other a solution of pyrogallic acid.
Pyrogallic acid, and the juice of walnuts, also stain the skin, although less intensely and permanently than nitrate of silver.
When strongly heated, gallic acid is converted into metagallic acid, or into pyrogallic acid, according to the manner in which the heat is applied.
It is distinguished from pyrogallicacid by its inferior insolubility in water, and by its not affecting the solutions of the protosalts of iron.
This is said to be prepared from harmless vegetable materials, but really consists of pyrogallic acid and nitrate of silver.
In this way a portion of pyrogallic acid is formed, which is very soluble in water, and strikes an intense bluish-black colour with the protosulphate or green sulphate of iron.
The exposed plate is then treated with reducing agents, as pyrogallic acid, ferrous sulphate, etc.
A salt of pyrogallic acid; an ether of pyrogallol.
Pyrogallic acid may be used for darkening the hair, not only in combination with metallic substances, but also by itself, or with alkalies.
Copper salts with certain substances, such as potassium ferrocyanide solution, potassium sulphydrate, calcium sulphydrate, and pyrogallic acid give dark-brown colorations.
Hair moistened with pyrogallic acid becomes under the influence of light and air dark gray to blackish.
Defn: A phenol metameric with phloroglucin, obtained by the distillation of gallic acid as a poisonous white crystalline substance having acid properties, and hence called also pyrogallic acid.
Defn: A red crystalline dyestuff, obtained by heating together pyrogallic and phthalic acids.
Defn: A salt ofpyrogallic acid; an ether of pyrogallol.
As the pyrogallic solution absorbs the oxygen it assumes a darker tint.
The poured inoculated plate should be placed over pyrogallicsolution under a sealed bell-glass and incubated at 37° C.
Buchner's cylinder, having a constriction near the bottom, is taken; and about two drachms of the pyrogallic solution are placed in the bottom of it.
After developing the image with iron, if it should, upon examination prove to be too thin, wash off the developer and apply pyrogallic acid and silver and bring it up to the required intensity.
Have any of your photographic correspondents tried developing their paper negatives with pyrogallic acid?
To determine the oxygen in the remaining gas, a portion of the caustic potash is allowed to flow out, and an aqueous solution of pyrogallicacid and potash is allowed to enter.
I beg to give the following method of preparing pyrogallic acid (first published by Dr.
I imagine the pyrogallic acid to possess a reducing influence on the salts of silver employed; but this effect is only produced by its combination with the hyposulphite of soda and chloride of silver.
In general the salts of iron are more adapted for positives, and weak pyrogallic acid solutions for negatives; say one and a half grain of pyrogallic acid, twenty minims of glacial acetic acid, and an ounce of distilled water.
The substances that can be employed as photographic developers are now somewhat numerous, but the most useful for negative making are pyrogallic acid (also known as pyrogallol, or for brevity as pyro.
Pyrogallic acid had been previously used as a hair dye, and also to a slight extent as a fur dye, so it was used in conjunction with the Ursol dyes for shading purposes.
It is then immersed in mercuric chloride for half an hour, and again intensified with pyrogallic acid.
The plate is then thoroughly drained, and the image is treated successively with a solution of platinic chloride, auric chloride, ferrous sulphate, and finally by pyrogallic acid, which has the property of solidifying the metallic deposits.
This is intensified by pyrogallic acid, and afterward washed with a pure water to which a little ammonia has been added.
What I claim for bromide of zinc is that a rapid plate can be made with it, and any degree of intensity can be readily obtained with a very small proportion of pyrogallic acid in the developer.
But, should your patients wish to hide their gray hairs, probably the best hair-dye that can be used safely is pyrogallic acid or walnut juice, the hairs being first washed with an alkaline solution to get rid of the grease.
With the plates to which I refer, I found that I only required to use for a 7½ × 5 plate one grain of pyrogallic acid in about three ounces of developer to get full density without the slightest difficulty.
The cry as always is to use plenty ofpyrogallic acid and you can get any amount of intensity.
Oxidized pyrogallic acid, a somewhat milder drug in its effect, has been highly commended, and has the alleged advantage of being free from toxic action.
Upon the whole, the best method in the average case is to curette thoroughly, and supplement with momentary cauterization, with caustic potash, or with several days' use of the pyrogallic acid ointment.
Ichthyol internally, and external applications of the same drug, and of resorcin, chrysarobin, and pyrogallic acid, have been extolled.
Until the pyrogallic solution was added, there was scarcely anything visible upon the specimen exhibited, the failure having in the first instance happened from the badness of the iodized paper.
The deposit in negatives is often much blackened by adding an increased proportion of acetic acid to the pyrogallic solution--say two drachms to the ounce, so that the solution shall be one-fifth of acetic acid.
A great advantage of the pyrogallic developer which I recommend, is that of its being able to be diluted to almost any extent, with no other result than simply making the development slower.
The developing agent with the pyrogallic and formic acids will keep good a very long time, longer, I think, than that in which acetic acid is used, but cannot be used as a dipping bath.
Physicians who were unacquainted with this energetic deoxidizing property of pyrogallic acid have proposed it as a substitute for chrysophanic acid in the treatment of skin diseases; but Dr.
Experiments were at once undertaken on rabbits, and proved that this catastrophe was due entirely to the pyrogallic acid pomade, and that the chrysarobine was innocuous.
He appears to have been submitted to a kind of experimental treatment in order to test the curative properties of pyrogallic acid as compared with chrysarobine.
Neisser has made known a case of poisoning by an ointment of pyrogallic acid, which at once shows that considerable danger attends its use for this purpose.
It was also found that in the case of the patient in the Breslau Hospital the pyrogallic acid had acted by its extreme avidity for oxygen when in contact with alkaline fluids.
An important gain in density may be obtained by exposing to sun or daylight a negative which has been developed and intensified with pyrogallic acid, fixation taking place after drying.
Immerse the plate a second time in the silver bath, and develop with either pyrogallic acid or sulphate of iron developer.
After the second washing, wash the prints over with a strong solution of pyrogallic acid, when the print will develop black, and the ground, if the washings were sufficient, will remain white.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pyrogallic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
