We have kept this separate from other reds derived from woods, because it is said (by Professor H. Dussance) to be obtainable not only equal in beauty and brightness to carmine, but of greater permanence. The process of preparation is as follows:--The powdered root exhausted by alcohol gives a solution to which hydrated oxide of lead is added in excess. The combination of colouring matter and lead oxide is then collected on a filter, washed with alcohol, dried, dissolved in acetic acid, and mixed with a quantity of water. The red being insoluble therein is precipitated, while the acetate of lead remains dissolved. After being washed, the colour is dried at a low temperature. The Professor affirms that the red so produced is unaffected by sulphuretted hydrogen, or by light and air; and it is stated that the colour which was used to paint the carriages of the Emperor Napoleon, remained as bright at the end of nine years as when it was put on. Possessing such properties, it is curious that the red has never been--in this country at least--introduced as an artistic pigment, the more especially as seventeen years have elapsed since its discovery. 116. _Silver Red._ By adding monochromate of potash to an acid solution of nitrate of silver, a particularly fine ochre-red is obtained. It is, however, apt to be injured both by foul air and exposure. 117. _Sorgho Red._ Some nine years back there was found to be a carmine colouring matter in most parts of the Chinese sorgho, chiefly in the unpressed stem. The red, which is extracted in an impure state, is dissolved in weak potash-ley, thrown down by sulphuric acid, and washed with water. This purified product, soluble in alcohol, caustic alkalies, and dilute acids, has been employed in Austria, Baden, &c., for the dyeing of silks and woollens with the common tin mordants. The colours produced from it are unchanged, they say, by warm soapsuds or light. We do not know whether the red found its way to England, but it has certainly not appeared here as a pigment. 118. _Thallium Red._ The orange-yellow precipitate formed by mixing a neutral salt of protoxide of thallium with bichromate of potash, is converted by nitric acid into an orange-red. The latter compound, which is a terchromate, is almost insoluble in cold water, 2814 parts being required to dissolve it. If the colour be boiled in a large excess of moderately strong nitric acid it is dissolved, yielding magnificent cinnabar red crystals on the solution cooling. These crystals likewise seem to be the terchromate. 119. _Tin Pink._