With coloured papers dyed by means of pigments, the colour of the ash left on ignition is some guide to the substance used, a red ash indicating iron oxide, a yellow ash chromate of lead, and so on.
This precipitates the chromate of lead as a yellow pigment.
Curarine chromate is distinguished from strychnine chromate by its amorphous character, and by its comparatively easy solubility.
Neutral lead chromate is insoluble in acids, but may be dissolved by potassic or sodic hydrates.
The crystals chromate does not dissolves it yellow, are cubical or tetra- colour it blue; with becoming deep red.
The only salts of chromium of toxicological importance are the neutral chromate of potash, the bichromate of potash, and the chromate of lead.
A solution of the chloride of barium obtained from (2) gives a yellow precipitate with neutral chromate of potash, insoluble in water, but soluble in nitric acid.
In one case[968] the breathing of chromate of lead dust seems to have been fatal; and there is also a double poisoning recorded by Dr.
The crystals chromate colours this sulphuric acid dis- of the hydrochloric solution a transitory solves it almost with- compound act on blue, then red.
The chromate of lead= is still more poisonous (see Art.
Chromate and dichromate of potassium give no precipitate with neutral salts of brucine; on the other hand, strychnine chromate is at once formed if present.
Any chromium present will now be in solution in the easily recognised form of potassic chromate (see "Chromium").
By boiling white lead with chromate of soda and subsequently treating with small quantities of sulphuric acid, American vermilion, or basic lead chromate, is prepared.
Although the color of this pigment is not very pleasing, it has proved itself to be the equal of zinc chromate in its protective value.
Unfortunately this zinc chromate was added to a formula containing a large percentage of lithopone, and the destruction of the lithopone to a great extent affected the value of this test.
Like the rest of the chromate pigments, it is a very slow-drying material, often requiring over a week to set up, unless considerable drier is added.
The neutral chromate of lead, made from either the nitrate or acetate of lead and chromate of soda, finds wide use as a tinting pigment.
Chrome yellow (chromate of lead) showed some action, as did also Prussian blue, the ash from the last named pigment showing a heavy percentage of iron oxide.
When a chromium compound is fused with an alkali and an oxidizing agent a chromate is produced.
When a dilute solution of a chromate or dichromate is acidified with an acid, such as sulphuric acid, no reaction apparently takes place.
The reason why the potassium salt rather than the sodium compound is used is that sodium chromate and dichromate are so soluble that it is hard to prepare them pure.
Since the chromate changes into a dichromate in the presence of an acid, it will be sufficient to study the action of the dichromates alone.
Note 8: Upon treatment with water the chromate passes into solution, the ferric hydroxide remains undissolved, and the excess of peroxide is decomposed with the evolution of oxygen.
Note 9: The addition of the sulphuric acid converts the sodium chromateto bichromate, which behaves exactly like potassium bichromate in acid solution.
Of the materials named, the chromate of lead makes the brightest color.
Gamboge, a transparent color, is very useful in mixture with Prussian blue; or chromate of lead and Prussian blue may be used.
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.
A valuable glue is made by an admixture with common glue of one part of acid chromate of lime in solution to five parts of gelatine.
Chromate of potash causes no precipitate in them, unless zinc or lead be present.
It occurs at Berezof in Siberia along with chromate of lead.
Eight parts of tartaric acid should be added to one of chromate to obtain a sure and rapid result.
A very fine unchangeable yellow may be communicated to ivory by steeping it 18 or 24 hours in a strong solution of the neutral chromate of potash, and then plunging it for some time in a boiling hot solution of acetate of lead.
We must, however, use dilute solutions of the chromate and acid, lest bitartrate of potash be precipitated, which will take place if less than 60 parts of water be employed.
The only ore of this metal, which occurs in sufficient abundance for the purposes of art, is the octohedral chrome-ore, commonly called chromate of iron, though it is rather a compound of the oxides of chromium and iron.
Watery solutions of chromate of potash and tartaric acid being mixed, an effervescence is produced which has the power of destroying vegetable colours.
The mineral acids react upon the chromate of potash only when vegetable colouring matter, gum, starch, or a vegetable acid are present, to determine the disengagement of gas.
Some manufacturers have contrived to effect the conversion of the oxide into an acid, and of course to form the chromate of potash, by the agency of potash alone, in a calcining furnace, or in earthen pots fired in a pottery kiln.
Whenever watery solutions of chromate of potash and tartaric acid are mixed, an effervescence takes place, during which the mixture possesses the power of destroying vegetable colours.
This chromate has a fine cinnabar red, when pure; and, at a dull red heat, parts with a portion of its oxygen and its mercurial oxide.
Chromate of lead, the chrome-yellow of the painter, is a rich pigment of various shades, from deep orange to the palest canary yellow.
It is yellow, and was at one time prepared as a pigment by calcining lead; but is now superseded by the chromate of this metal.
The filtrate may contain phosphate of potassa, originating from the phosphate of lime present, and chromate of potassa, resulting from the oxidation of the sesquioxide of chromium.
Two glass tumblers to hold the solution, a pair of battery zincs, a pair of carbons, and a bi-chromate of potash solution, are needed.
If you wish to use a dry-cell instead of the pair of bi-chromate cells, you can place the cell upon the floor and make the wires connecting it to the motor long enough so the truck can run back and forth across a room.
When through playing with the truck, however, it is important to remove both pairs of elements and wash them off, because the bi-chromate solution attacks the zinc elements even when the current is not in use.
As the bi-chromate solution stains very badly, it is advisable to operate the motor truck only where there is no danger of ruining anything in case some of the solution spills, as in the basement or workshop.
To reduce the eating away of a zinc pencil used in a bi-chromate solution, the zinc should be amalgamated by rubbing a thin coat of mercury over its surface.
As the bi-chromate solution attacks the zinc element of a cell even when the current is not being drawn upon, the zinc should be removed when the cell is not in use.
Chlorides are estimated by titrating the neutral solution with N/10 silver nitrate solution, potassium chromate being used as indicator.
N/10 silver nitrate solution, using a neutral solution of potassium chromate as indicator.
Or you may reverse this order and steep first in the sugar-of-lead solution, then in that of chromate of potash.
Immerse for a day or two in a solution of chromate of potash, then for a few minutes in boiling-hot solution of sugar-of-lead.
If much more chromate be used than that ordered the result is a blue-black.
A metal discovered in native chromate of lead by Vauquelin in 1797.
It is found in the state of oxide, combined with oxide of iron, in some abundance, in the Shetland Islands, and elsewhere; as chromate of lead it constitutes a very beautiful material.
Both the chromateand the bichromate of potassium are extensively used in dyeing and calico-printing.
The whole quantity of chromate used should not exceed 1/4 oz.
The chloride of chromium is again precipitated with carbonate of lime, and by ignition converted into chromate of lime.
From chromate of barium, decomposed by concentrated nitric acid.
This oxidation may be effected very readily if the chrome ore reduced to very fine powder be mixed with a carbonate of one of the metals of the alkalies or alkaline earths, a chromate of the base being formed.
The chromates of commerce are prepared from either chrome ore orchromate of potassium.
Defn: Chromate of copper and lead, of various shades of green.
The yellow colour consists of the light kind of chromate of lead, for the eyes bisulphate of mercury, and for the stand the deeper varieties of chromate of lead, or orange chrome.
Bi-chromate of potash is a still more deadly poison.
If a mixture of potassium chromate and potassium chloride, containing approximately equal (0.
Potassium chromate is used as a favorite indicator in quantitative analysis, for this purpose.
This salt happens to be very difficultly soluble, and to be colored red, as well, so that silverchromate is precipitated and is immediately recognizable.
Each molecule of silver chromate forms two silver ions when it is ionized.
A further solution of 1 part of potassium chromate (not bichromate) in 100 parts of water is prepared, and is added very gradually to the other solution with constant agitation.
Blue inks are made with indigo or Prussian blue; yellow with lead chromate or yellow ochre; green is made by mixing yellow and blue; and purple by mixing red and blue.
In chemical phraseology, the manufactured article is the chromate of lead, since the chromate is separated from the iron by the aid of a solution of the nitrate or acetate of lead.
Chrome yellow is extensively manufactured in Baltimore, from the chromate of iron, found near that city.
The serpentine rock appears, in nearly every locality examined, to be highly charged with particles of chromate of iron.
Each was treated repeatedly with a saturated solution of ammonium acetate until the filtered ammonium acetate solution gave no appreciable precipitate with potassiumchromate solution.
The presence of lead was demonstrated by the black precipitate with hydrogen sulphid, the yellow precipitate with potassium chromate and the typical yellowish crystalline precipitate with potassium iodin.
If at the end of a fortnight in the case of small bronzes, or in three to six weeks for large objects, the water shows no cloudiness, or if upon the addition of yellow potassiumchromate it instantly assumes a red colour (p.
The method of titration with yellow potassium chromate is not applicable here, for the free acid prevents the appearance of the red precipitate.
Are you now in the management of the chromate of iron quarries in Unst?
The only kind of work in Unst is at the chromate ore quarries; but they can only employ a very limited number of men compared with the population, and those who work in the quarries in winter generally work in summer also.
Have you been working lately in the chromate of iron quarries?
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "chromate" in a variety of sentences. We hope that you will now be able to make sentences using this word.
