This gelatine film is, when required for use, sensitised by immersion in a solution of bichromate of potassium, methylated spirits, and water.
The process under consideration, in common with some others, is based upon the fact that gelatine or albumen sensitised with bichromate of ammonium or potassium, becomes insoluble after being acted upon by light.
In the albumen process the sensitive film is composed of egg albumen, bichromate of ammonium or potassium, and water, which is spread upon a zinc plate.
When recrystallized bichromate is not procurable, a few drops of liquid ammonia added to solution of crude bichromate is recommended.
Into a dish of sufficient depth pour in the one in ten bichromate solution to a depth of about one inch, and immerse your paper sheet by sheet, until you have in it all you intend to sensitize.
With constant strength of bichromate and gum, uniform weights and combination of pigment, similarity of repeats are obtained: but these can only be secured when each sheet of paper is coated identically with its fellow.
In hot weather it is recommended that the solution of recrystallized bichromate be made immediately before using, as in dissolving the crystals a considerable reduction of temperature is produced.
If the bichromate is used only in the pigmented gum, without previous saturation of the paper, exposure must be much more prolonged.
Some of the most proficient workers of the process adopt the easier one of coating the paper, without previous preparation, with a mixture of gum, bichromate of potass and pigment.
If a hard negative has to be dealt with, a stronger solution, or longer soaking in the bichromate solution, is all that is needed; for weak negatives vice versa.
When paper is coated with a mixture of gelatine pigment and a bichromate salt, dried under favourable conditions and exposed to light under a negative it naturally follows that a positive image is produced.
The stains above alluded to are caused by the chemical combination of bichromate with the lead of the paint, forming chromate of lead or chrome yellow.
For working by the previously chromated paper method, the sensitizing solution is made up of one part of bichromate of potassium dissolved in ten parts of water.
If ice is placed in the bichromate bath allowance must be made by keeping out part of the water.
Apply this to the wood, and when dry treat with a solution of bichromate of potash in the same proportion as with the catechu.
Bichromate of potash alone in water will give a good stain.
Ponton used a paper saturated with bichromate of potash, and this was one of the earliest photogenic processes.
It will likewise find an application in laboratories, where the bichromate pile is in much demand because of its powerful qualities, and where it is often necessary to order it from quite a distant point.
In order to do away with this inconvenience, which is inherent to all bichromate piles, Mr. G.
Apparatus for Maneuvering Bichromate of Potassa Piles from a Distance.
Potassium bichromate and sulphuric acid oxidize it to carbon dioxide and acetic acid, while alkaline potassium permanganate oxidizes it to carbon dioxide.
It may be artificially prepared by the hydrolysis of isopropylcyanide with alkalies, by the oxidation of isopropyl alcohol with potassium bichromate and sulphuric acid (I.
Stains produced from drugs and chemicals include such materials as logwood, bichromate of potash, ammonia, iron sulphate, acetate of iron, etc.
It was made of white wood, and, after being assembled, was stained a rich brown by receiving two coats of bichromate of potash.
Bichromate of potash comes in the form of lumps and crystals.
A very beautiful golden-brown finish may be given these stools by first coating them with bichromate of potash.
The union of chlorine with hydrogen gas, the blackening of silver salts, the reduction of bichromate of potash and of certain ferric salts in contact with organic substances, are all familiar instances of the action of light.
Now the woolen dyer has largely adopted an excellent mordant in bichromate of potash; it is cheap, easily applied, and not perceptibly injurious to the fiber.
With Bichromate of Potash as mordant, Old Fustic gives old gold colour.
Mordant the wool with 3% ofBichromate of Potash, then boil with the lichen for 1 hour or more.
Mordant with 3 per cent Bichromate of Potash and boil wool in it for 1-1/2 hours.
Mordant with 3% Bichromateof Potash for 45 minutes.
They dye good but fugitive red with bichromateof potash, or alum.
The bright yellow Lichen, growing on rocks and walls, and old roofs, dyes a fine plum colour, if the wool is mordanted first with Bichromate of Potash.
According to Benz the first two do not remove the sulphuretted hydrogen completely, and oxidise the acetylene to some extent; while potassium bichromate leaves some sulphur and phosphorus behind in the gas.
The permanganate or bichromate solution is standardized by dissolving 0.
After the oxidation is finished, the mass is taken from the furnace and cooled; the bichromate is obtained by lixiviation, treated with sulphuric acid and crystallized.
If, instead of chromate or bichromate of potash or soda, chromic acid is sought, the mass after lixiviation is treated with sulphuric acid, and the chromic acid is obtained directly without any intermediate steps.
Dilute sulphuric acid is used as the exciting fluid, and in this is dissolved the bichromate of potash which keeps the hydrogen bubbles from the carbon plate.
Bichromate of Potash Cells= are very useful for general laboratory work.
Boil for twenty minutes and then add about half a teaspoonful of powdered bichromate of potash, stirring with a glass rod.
The frustules adhere near their ends and are so firmly fastened that boiling in nitric acid and bichromate of potash for fifteen minutes will not separate them.
To sensitize the paper, it is dipped for a couple of minutes in a solution of potassium bichromate (1 in 25), then taken out and dried in the dark.
The light acts on the bichromate in such a way as to render the gelatine insoluble.
The carbon film contains gelatine and bichromate of potassium.
On the small scale this salt may be prepared from the bichromate by neutralising it with hydrate of potassium.
By adding 1% of bichromate of potassa to the acid before rectifying it.
Chromate and bichromate of potassium give yellow precipitates insoluble in dilute nitric acid, and soluble in solution of potassium hydrate.
Others boil the fat along with water and a little dilute nitric or chromic acid, or a mixture of bichromate of potash and sulphuric acid; and afterwards wash it thoroughly with water.
If to a mixture of morphia and oil of vitriol a minute fragment of bichromate of potassium be added, oxide of chromium is set free, and a fine green colour developed.
A solution of equal parts of nitre and either chromate or bichromate of potash, in water.
These are treated with a solution of chromic acid, or with a solution of bichromate of potassa, or some mineral acid, as noticed at No.
Bichromate of potassium, 2 parts; nitrate of potassa, 1 part; and white sugar, 3 parts.
Dilute acids convert it into benzoic acid, grape sugar, and saliretin; and with a mixture of sulphuric acid and bichromate of potassa it yields a large quantity of salicylous acid.
A simple solution of chromate or bichromate of potash in distilled water.
The Committee calls attention to the fact that occasionally potassium bichromate is found containing sodium bichromate, although this is of rare occurrence.
When sugar is present the bichromatewould be reduced by the sugar, hence this method is not applicable.
From the amount of bichromate reduced calculate the percentage of glycerol.
Before the bichromate is added to the glycerine solution it is essential that the slight excess of lead be precipitated with sulphuric acid, as stipulated.
Filter the acid solution into a 25 cubic centimeter graduated flask; bring to the mark with water and determine the glycerine by the bichromate method as described under glycerine analysis.
An approximation to the quantity can be obtained from the spread between the acetin and bichromate results on such distillates.
On pure glycerines the results are identical with those obtained by the bichromate process.
A correction for the non-volatile impurities may be made by running a bichromate test on the residue at 160deg.
It is never safe to assume this salt to be constant in composition and it must be standardized against the bichromate as follows: dissolve 3.
It is necessary that fractured articles should be exposed to the light after being mended, and then warm water will have no effect on them, the chromate of lime being better than the more generally used bichromate of potash.
Dissolve also a small quantity of bichromate of potash in distilled water, and mix both solutions together.
It is made by adding to the common India ink of commerce about one per cent, in a very fine powder, of bichromate of potash.
Those who cannot provide themselves with ink prepared as above in a cake, can use a dilute solution of bichromate of potash in rubbing up the ink.
It is afterwards put into a second bath, which contains fifty parts of burnt umber ground in alcohol, twenty parts of lampblack, ten parts of English glue, and ten parts of bichromate of potash in 500 parts of water.
It can be bought from a dealer, or one can be made in a simple form by taking a jar and filling it with a strong solution of bichromate of potassium, to which a little sulphuric acid has been added.
If a strong battery which will only work the coil for a short time is required, the bottle bichromate is a good one.
The drawing is photographed to the required size (as before), and the negative laid upon a glass plate (previously coated with a mixture of gelatine and bichromate of potash).
The titration may be done with a standard solution of (1) permanganate of potash, or (2) bichromate of potash.
The method resembles in its working the bichromateiron assay.
The iron, of course, must be in excess, which excess is determined when the ore is dissolved by titrating with standard permanganate or bichromate of potash solution.
Either permanganate orbichromate of potash is generally used for this purpose.
When calcination is not admissible it may be destroyed by heating with strong sulphuric acid and bichromate or permanganate of potash or by fusion with nitre.
The bichromate is run in, in a steady stream, the assay solution being continuously stirred until the reaction is sensibly slackened.
In about an hour the decomposition is complete, and the solution is diluted with cold water, and titrated with the solution of bichromateor of permanganate of potassium.
In solutions rendered faintly acid with acetic acid, they give a yellow precipitate with bichromate of potash.
It is used as an oxidising agent in a similar manner as permanganate and bichromate of potash, especially in the determinations of copper, arsenic, antimony, and manganese.
Cool and titrate the remaining ferrous iron with the permanganate or bichromate of potassium solution.
The bichromate method has the advantage of a standard solution which does not alter in strength, and the further one of being but little affected by altering conditions of assay.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "bichromate" in a variety of sentences. We hope that you will now be able to make sentences using this word.
