=Naples Yellow.=—This handsome pigment, which is, unfortunately, susceptible to the action of sulphuretted hydrogen, is known commercially under different names. Naples yellow takes its names from the fact that it was formerly exclusively made in Italy, where the method was kept secret, a secret which disappeared with the advance of analytical chemistry. Naples yellow is now known to be lead antimoniate. Naples yellow is a handsome pigment. Its preparation is more tedious than that of chrome yellow, hence it is now rarely employed. The author has had practical experience that much of the so-called Naples yellow of commerce is nothing but a suitably shaded chrome yellow. Naples yellow can be prepared by different methods. According to the oldest, given by Brunner, 1 part of pure tartar emetic is carefully and thoroughly ground with 2 parts of lead nitrate and 4 parts of common salt. The mixture is melted at a low heat in a Hessian crucible, and the fluid mass poured on a cold iron plate. After cooling, it is boiled out with water, when lead antimoniate remains as a powder of a more or less deep yellow colour. It is not easy to obtain this favourable result with certainty in every case. If a certain temperature is exceeded only by a little, a hard mass results, which by long boiling does not become a fine powder, but a sandy substance of little brilliance. Even when the operation succeeds, the product often varies considerably in shade, sometimes a sulphur yellow, at other times an orange pigment being formed. As a rule, the paler product is obtained at a lower temperature; by stronger heating, darker products of a red shade are obtained. According to another recipe, 2 parts of tartar emetic are melted with 4 parts of lead nitrate and 8 parts of common salt. The mass is treated with very dilute hydrochloric acid for a long time, which extracts some quantity of lead oxide, a deeper product being thus obtained. Care is, however, necessary in this treatment; acid of too great strength would spoil the whole product. The Paris method for Naples yellow is as follows: metallic antimony is oxidised by melting in air; to 12 parts of antimony, 8 parts of red lead and 4 parts of zinc oxide are used, and the mixture is melted at a low red heat. A cheap, but not particularly bright product, can be obtained from old printer’s type. The metal, which is an alloy of antimony and lead, is powdered, mixed with 3 parts of saltpetre and 4 parts of common salt, melted, and the mass washed out with water.