It is tasteless, colourless and odourless gas, which is exceedingly stable and inert.
When perfectly pure, carbon bisulphide is a colourless, somewhat pleasant smelling, highly refractive liquid, of specific gravity 1 2661 (18°/4°) (J.
The colour varies somewhat with the chemical composition, being grey or colourless in chlorargyrite, greenish-grey in embolite and bromargyrite, and greenish-yellow to orange-yellow in iodembolite.
These are washed with ammonium chloride until the filtrate is colourless, ignited, fused with caustic potash and nitre, the melt dissolved in water and nitric acid added to the solution until the colour of potassium ruthenate disappears.
Potassium ruthenium cyanide, K4Ru(CN) 6.3H 2 O, formed when potassium ruthenate is boiled with a solution of potassium cyanide, crystallizes in colourless plates which are soluble in water.
If the bead is coloured we may have present: cobalt, blue to violet; copper, green, blue on cooling; in the reducing flame, red when cold; chromium, green, unaltered in the reducing flame; iron, brownish-red, light-yellow or colourless on cooling; in the reducing flame, red while hot, yellow on cooling, greenish when cold; nickel, reddish to brownish-red, yellow to reddish-yellow or colourless on cooling, unaltered in the reducing flame; bismuth, yellowish-brown, light-yellow or colourless on cooling; in the reducing flame, almost colourless, blackish-grey when cold; silver, light yellowish to opal, somewhat opaque when cold; whitish-grey in the reducing flame; manganese, amethyst red, colourless in the reducing flame.
If the hot bead is colourless and remains clear on cooling, we may suspect the presence of antimony, aluminium, zinc, cadmium, lead, calcium and magnesium.
If the hot colourless bead becomes enamel-white on cooling even when minute quantities of the substances are employed, we may infer the presence of barium or strontium.
The colour produced is generally of a greenish shade; for example, nitrosobenzene is green when fused or in solution (when crystalline, it is colourless), and dinitrosoresorcin has been employed as a dyestuff under the names " solid green " and " chlorine."
As a general rule, hydrocarbons are colourless; the exceptions include the golden yellow acenaphthylene, the red bidiphenylene-ethylene, and the derivatives of fulvene CH: CH >CH 2, which have been discussed by CH: CH J.
With basic substances, the chromophoric combination with a colourless acid is generally attended by a deepening in colour; auxochromic combination, on the other hand, with a lessening.
Examples of the first case are found among the colourless acridines and quinoxalines which give coloured salts; of the second case we may notice the colourless hydrochloride and sulphate of the deep yellow o-aminobenzophenone.
With acid substances, the combination with " colourless " metals, i.e.
Mention may be made of the phenomenon of halochromism, the name given to the power of colourless or faintly-coloured substances of combining with acids to form highly-coloured substances without the necessary production of a chromophoric group. The researches of Adolf von Baeyer and Villiger, Kehrmann, Kauffmann and others, show that this property is possessed by very many and varied substances.
He has also shown that the nitrophenols yield, in addition to the colourless true nitrophenol ethers, an isomeric series of coloured unstable quinonoid aci-ethers, which have practically the same colour and yield the same absorption spectra as the coloured metallic salts.
(3) If a colourless compound gives a coloured one on solution or by salt-formation, the production of colour may be explained as a particular form of ionization (Baeyer), or by a molecular rearrangement (Hantzsch).
From its aqueous solution, concentrated hydrochloric acid precipitates hydrocobalticyanic acid, H 3 Co(CN) 61 as a colourless solid which is very deliquescent, and is not attacked by concentrated hydrochloric and nitric acids.
Uracil and its homologues may be obtained in many cases from the hydrouracils by the action of bromine, and subsequent elimination of the elements of hydrobromic acid; or by the condensation of aceto-acetic ester and related substances with urea, thiourea, guanidine, &c. Uracil, C4H402N2, crystallizes in colourless needles, is soluble in hot water and melts with decomposition at 335° C. Hydrouracil, C4H602N2, is obtained by the action of bromine and caustic alkalis on succinamide (H.
Cyanogen is a colourless gas, possessing a peculiar characteristic smell, and is very poisonous.
It burns with a purple flame, forming carbon dioxide and nitrogen; and may be condensed (by cooling to - 25° C.) to a colourless liquid, and further to a solid, which melts at - 34.4° C. (M.
Boron dissolves in molten aluminium, and on cooling, transparent, almost colourless crystals are obtained, possessing a lustre, hardness and refractivity near that of the diamond.
It is a colourless pungent gas which is exceedingly soluble in water.
A saturated solution of the gas, in water, is a colourless, oily, strongly fuming liquid which after a time decomposes, with separation of metaboric acid, leaving hydrofluoboric acid HF BF3 in solution.
Boron fluoride also combines with ammonia gas, equal volumes of the two gases giving a white crystalline solid of composition BF 3 NH 3 i with excess of ammonia gas, colourless liquids BF 3.2NH 3 and BF 3.3NH 3 are produced, which on heating lose ammonia and are converted into the solid form.
It is a colourless fuming liquid boiling at 17-18° C., and is readily decomposed by water with formation of boric and hydrochloric acids.
It is a colourless fuming liquid boiling at 90.5° C. With water and with ammonia it undergoes the same reactions as the chloride.
By the action of zinc methyl on ethyl borate, in the requisite proportions, boron trimethyl is obtained, thus :-2B(OC2H5)2+ 6Zn(CH 3) 2 =2B(CH 3) 3 +6Zn< OC2H5 as a colourless spontaneously inflammable gas of unbearable smell.
(0C2H5)5 is obtained as a colourless liquid of boiling point 112° C. Boron triethyl and boron trimethyl both combine with ammonia.
It is a colourless oil, which boils at 247° C. (745 mm.), and when pure is almost odourless.
Nicotimine is a colourless liquid which boils at 250 0 -255° C. Its aqueous solution is alkaline.
Metals producing colourless salts with acids, is attended by colour changes contrary to those given above, auxochromic combination being accompanied by a deepening, and chromophoric by a lessening of the tint.
In the free state these substances are colourless, and were assumed to have the formula shown in i.
On the chromophoreauxochrome theory (the nitro group being the chromophore, and the hydroxyl the auxochrome) it is necessary in order to explain the high colour of the metallic salts and the colourless alkyl and aryl derivatives to assume that the auxochromic action of the hydroxyl group is only brought strongly into evidence by salt formation.
Hantzsch explains the transformation of the colourless acid into red salts, which on standing yield more stable, colourless salts, by the following scheme: N R.0N O H R CA O R'CC NO 2Na 2 O?
N N Colourless, stable.
(13) The substance dissolves slowly and in small quantity, and forms a colourless bead which remains so on cooling.
The crude product is very impure and possesses an offensive smell; it may be purified by forcing a fine spray of lime water through the liquid until the escaping water is quite clear, the washed bisulphide being then mixed with a little colourless oil and distilled at a low temperature.
It is colourless and contains definite corpuscles, which are round or elliptical, and in many Metanemertines are coloured red by haemoglobin, being colourless in other species.
It contains a colourless fluid, with flat, oval, nucleated corpuscles, as a rule colourless, but in some cases tinged with yellow or red haemoglobin.
The acid is thus obtained in colourless rhombic prisms of the composition C 6 H 8 0 7 +H 2 0.
Its specific gravity of 4.5 is about twice as great as that of salt and of many other colourless, transparent and glassy minerals not unlike barytes in general appearance.