CELAVINIA (also spelt celavina and cevalina) has been on the English market since 1905, but has only lately been sold in large quantities. The scarcity of some of the popular tanning materials since the outbreak of the European War resulted in enquiries for materials that were very little known, and celavinia has proved worthy of attention. It consists of the seed pods of the tree _caesalpinia tinctoria_, which grows abundantly in certain districts of Central and South America. The pod is from 4 to 6 in. long and is flaky when dried. It contains 30 to 32 per cent, of tannin of the pyrogallol class, and gives a very light-coloured and almost white leather. It is the only pyrogallol tannin which does not deposit bloom, or ellagic acid, on the leather. It may be used as a substitute for sumach in tanning, but has not the same bleaching effect in the retanning process. A tanning extract of celavinia would be useful for some classes of light leathers, where paleness of tint is important. It is difficult to make a second extraction of tannin in the case of the natural material, as, after the first extraction, it forms a soft pulp, through which water will not easily percolate. HEMLOCK (_abies canadiensis_) is an important tanning material, both the bark and the wood being extensively used in America. The wood is now generally converted into extracts in factories built near the principal forests. Of late years, this extract has been imported into the United Kingdom in fairly large quantities, in order to produce a cheap red sole leather to compete with the American hemlock-tanned leather. It contains only about 25 per cent. of tannin, but its value is increased by its contents of insoluble non-tannins, which give weight and solidity to the leather. Hemlock really gives a strong, durable leather, but in America the practice of using artificial weighing materials, such as glucose and Epsom salts, with a reduced quantity of tanning material, has considerably lowered the value of this leather. In addition to the materials described, there are several of minor importance which can only be briefly mentioned. LARCH BARK is obtained from the tree _larix Europea_, which is found in Scotland and North Europe. It contains 10-12 per cent. of tannin, which gives a light colour and pleasant odour to leather. Scotch basils (sheep skins) are tanned with this bark.