Sympathetic ink, a writing fluid of such a nature that what is written remains invisible till the action of a reagent on the characters makes it visible.
It is a powerful flux, and is used as a substitute for borax as a blowpipe reagent in testing for the metallic oxides.
It is employed chiefly in the production of sulphuric acid, and as a reagent in bleaching; -- called also sulphurous anhydride, and formerly sulphurous acid.
Defn: An insoluble substance separated from a solution in a concrete state by the action of some reagent added to the solution, or of some force, such as heat or cold.
Defn: That which saponifies; any reagent used to cause saponification.
Defn: Any force or reagent which causes the formation of a precipitate.
A chemical bath orreagent used in developing photographs.
One very common method is to spot the fabric, that is to put a drop of the reagent on it, usually with the aid of the stopper of the reagent bottle, and to observe the colour changes, if any, which ensue.
This describes the fact that when the precipitating reagent is added very slowly, or a little at a time, a larger amount must be used, and the slower the addition the greater the excess required.
Rideal also states that in the case of an acid bone gelatine, a good peroxide of lime is almost an ideal reagent for bleaching, inasmuch as "the lime carries down phosphate, several impurities and colouring matters.
This reagent is usually added to the sol, after evaporation and before gelation.
Before taking up the theory of the separation of these groups by precipitation with hydrogen sulphide in the presence of a strong acid, a discussion of some of the characteristics of the reagent will be in place.
The reagent is prepared as follows: (1) Phosphotungstic acid 25 gm.
Neither precipitation of phosphates as a light flocculent sediment nor simple decolorization of the reagent should be mistaken for a positive reaction.
The reagent consists of pure nitric acid, 1 part, and saturated aqueous solution of magnesium sulphate, 5 parts.
It is more sensitive than Heller's test, of which it is a modification, and has the additional advantage that the reagent is not so corrosive.
Uffelmann's reagent as follows: In a test-tube mix three drops concentrated solution of phenol and three drops saturated aqueous solution of ferric chlorid.
The reagent consists of a saturated aqueous solution of trichloracetic acid to which {72} magnesium sulphate is added to saturation.
This reagent is quite stable if kept in a dark glass bottle.
In a test-tube take equal parts of the urine and Obermayer's reagent and add a small quantity of chloroform.
The reagent may then be observed to flow across the field and come into contact with such of the micro-organisms as lie in its path.
Nessler reagent to each glass by means of a clean pipette.
Reagent required: Any one of the liquid waterproof black drawing inks (Chin-chin, Pelican, etc.
Arsenious oxide is also used as a chemical reagent in glass making and in the dye industry.
It is largely used in the laboratory as a reagent to detect the presence of sulphuric acid or soluble sulphates.
A great deal of sodium sulphite is used in the bleaching industry, and as a reagent for softening paper pulp.
The acid is therefore used as a reagent to precipitate potassium in analytical work.
Whenever one of the operations is repeated, the strength of the reagent is successively diminished.
The first mention of nitric acid is in connection with this purpose, and, therefore, the early history of this reagent becomes the history of the process.
It is apparent from the uses to which this reagent was put in separating gold and silver, from the method of clarifying it with silver and from the red fumes, that Agricola could have had practical contact only with nitric acid.
Dr Ramon Cordina Langlies states that the best reagent for the examination of olive oil is that of Hauchecorne.
This acid is a very delicate test reagent for iron.
Any reagent which will remove the writing will, of course, destroy the pattern below, and so render the alteration evident.
Dr de Vrij prefers the employment of the iodosulphate of chiniodine as a reagent for the detection and estimation of quinine.
He also employs a saturated solution of bichromate of potash in sulphuric acid, which he uses in the same proportion as before; but in this case the oil and the reagent are always stirred together.
This reagent serves to detect minute traces of iodine in insoluble as well as in soluble compounds of that element.
Notwithstanding the different circumstances in which the reagentwas applied, the results are satisfactory.
This reagentis composed of three parts of pure nitric acid at 40 deg.
The acid metantimoniate of potassium is the only reagent which yields a precipitate with the sodium salts, and is therefore of great value in chemical analysis.
The product obtained when this reagent is used is generally termed vulcanised fibre.
Most papers, however, show an acid reaction when tested with litmus, the usual reagent employed by those not familiar with the proper methods of testing paper.
There is no chemical reagent known which will produce a colour reaction on a paper containing straw that will serve to distinguish it from a paper containing esparto.
The flow of the water and chemical reagent is adjusted by previous analysis.
The use of aniline sulphate can also be resorted to, and for microscopic work the most useful reagent is a mixture of zinc chloride and iodine.
If the tannin reagent produces no precipitate, reduce with hydrochloric acid and zinc, or ammonia and zinc, and neutralise and filter as in the case of a basic dye.
The phloroglucine reagent fails as a test for mechanical wood in papers which have been dyed with certain aniline colours, for example, metanil yellow.
This produces a brown stain on the paper, but it is not a desirable reagent for ordinary office purposes.
If the presence of micro-organisms be suspected, harden in methylated spirit or absolute alcohol, but as a rule both for diseased organs and tumours Müller’s fluid will be found the most satisfactory reagent for general use.
This instrument is required for transferring sections from one reagent to another, or from oil of cloves, &c.
Osmic acid is also a most valuable stainingreagent (see p.
In using this reagent it should be filtered into a watch glass, and the sections placed in it for at least an hour.
Its most important use, however, is as a reagent in photography, large quantities being manufactured for use as a chief agent in toning photographic prints.
The precipitate containing the gallium concentrated in a small bulk, is redissolved in acid, and the excess of the latter reagentremoved by evaporation, after which it is boiled with much water.
As a chemical reagent it is employed chiefly in detecting certain organic acids.
It turns red with only a trace of acid, and blue with the least trace of alkali, and so forms a very delicate reagentwhen pieces of paper are soaked with it, and dipped into the liquids to be tested.
As a chemical reagent its action is almost precisely like that of caustic soda, though it is usually considered a stronger base, as K is a more electro-positive element than Na.
Put one drop H2SO4 from the reagent bottle in 10 cc.
Its use as a reagent in the laboratory is illustrated by the following experiment:-- Experiment 49.
Hydrogen sulphide or sulphuretted hydrogen, H2S, is employed chiefly as a reagent in the chemical laboratory.
Phelps found that ortho-tolidine in acetic acid solution produced an intense yellow colouration with free chlorine and suggested the use of this reagent as a qualitative test for chlorine.
On adding this reagent a blue colouration is produced but on stirring it rapidly changes to a bright yellow which is proportional in intensity to the amount of free chlorine present.
Fe) give a blue colouration with the starch-iodide reagent and for this reason it is always advisable, whenever possible, to make a control test on the untreated water.
There have recently been two new reagents introduced which act as catalyzers in splitting fats, just as the Twitchell reagent acts, but the fatty acids produced by the cleavage are of good color.
Recently the Twitchell double reagent has been introduced through which it is claimed that better colored fatty acids are obtained and the glycerine is free from ash.
The Twitchell process of saponification consists of causing an almost complete cleavage of fats and oils by the use of the Twitchell reagent or saponifier, a sulfo-aromatic compound.
The Pfeilring reagent is very similar to the Twitchell reagent, being made from hydrogenated castor oil and naphthalene by sulfonation with concentrated sulfuric acid.
These are the Pfeilring reagent and Kontact reagent.
The slow addition of the reagent is essential, and the stirring not less so.
In all precipitations the reagentshould be added slowly, with constant stirring, and should be hot when circumstances permit.
While a large excess will do no harm, the cost of this reagent is so great that waste should be avoided.
The reagent employed is sodium arsenite in the presence of sodium bicarbonate.
The slow addition is less likely to occasion contamination of the precipitate by the inclosure of other substances which may be in the solution, or of the reagent itself.
Add to the clear liquid one or two drops of silver nitrate solution, to make sure that an excess of the reagentis present.
The stoppers of reagent bottles should never be laid upon the desk, unless upon a clean watch-glass or paper.
I merely remark in passing that I gave orders to set aside a still greater fund toward finding a reagent against the Grass, and to put those who had lately assisted Miss Francis in charge.
September 17: The enthusiasm greeting the discovery that F's reagent mortally affected the Grass was only tempered by the dampening thought that its action had been incomplete.
Seidell has shown that if the vitamine is absorbed by Lloyd's reagent and this reagent be then extracted with dilute alkali the vitamine passes into the alkaline solution.
In these cases the vitamine was carried by Lloyd's reagent and administered mixed with cereal, or the crude extract was combined with the milk.
In preparing the Grignard reagent the commencement of the reaction is accelerated by a trace of iodine.
The reagent is added till no further precipitate is produced, which is known by filtering a small portion at intervals and testing with the potassio-mercuric iodide to see if finished.
With this reagent strychnia gives a pale, other alkaloids a bright yellow flocculent precipitate, in very dilute solutions.
But if the poison has been discovered, the solution reserved in the burette should be evaporated, dissolved in water and a little dilute acid, avoiding heat, and titrated by Mayer’s reagent to ascertain the quantity.
This arrangement prevents loss of HCN by volatilization, and also, with a little care, avoids any danger of the reagent dropping back into the solution.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "reagent" in a variety of sentences. We hope that you will now be able to make sentences using this word.
