Of These There Are Three Tints Deep A So-called Pale And Lemon





TTITLE DEEP CADMIUM.



Cadmium Yellow is comparatively a recent introduction, the metal itself

not having been discovered till 1818. The cadmium yellows of commerce

are (the chromate excepted) all sulphides, and therefore not affected by

impure air. Until lately, they were not manufactured in England but

imported from abroad, and as a rule were sadly doctored. We have found

in them a large proportion of orpiment, chromate of lead, &c., together

with quantities of soluble salt, extracted by boiling water. Owing to

careless preparation, there was also present an unnecessary amount of

dirt, which interfered as much with the purity of the colour, as

sophistication lessened its stability. For these reasons, doubtless,

cadmium yellows got to be regarded by some with disfavour and suspicion;

and it may fairly be said that they did not attain their present

popularity, until they became an article of home produce.



Deep cadmium yellow, if genuine, may without hesitation be declared

permanent, both with respect to foul gas, and exposure to light or air.

The variety under notice is of extreme depth, inclining to orange,

glowing, lustrous, and brilliant. It is not very transparent, but

wonderfully clear and bright, of great power, and the most richly toned

yellow known. For draperies it is particularly adapted, and for gorgeous

sunsets is invaluable. It works and washes well, readily throws all

other yellows into the shade when used alone, and combines admirably

with Chinese white for the light touches of bright clouds or mountains.



By admixture with white, cadmium gives a series of beautiful clear

tints. When compounded with white lead, however, the colour has been

stated to be destroyed. Theoretically, this might very well happen.

Cadmium yellow is composed of cadmium and sulphur--white lead of lead

and carbonic acid. If the former parted with some of its sulphur to the

latter, sulphide of lead would result, which is black. Hence, the partly

decomposed yellow and white would be mixed with black, and there would

be formed a blackish-yellow or a yellowish-black. Again, if the cadmium

parted with the whole of its sulphur to the lead, receiving in exchange

the carbonic acid of the latter, a mixture of black sulphide of lead

with white carbonate of cadmium would be furnished, the result being a

grey. Perhaps the following rough diagram may serve to make our meaning

plainer:--





Of The Gold Coast The Cape And Natal Turacine The Name Proposed Of Those Pigments Would Do The Rich Yellowness Entirely Disappearing facebooktwittergoogle_plusredditpinterestlinkedinmail

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