Another writer in _Industries_ says that the manufacture of ultramarine has perhaps hardly received the attention it deserves in England. The importance of the industry has been recognised in Germany, however, and though the palmy days of the trade, when the whole production was in the hands of a few firms, and the price was a matter of private friendly arrangement, are gone for ever, yet the business is in a flourishing state, and should prove lucrative if properly managed. It is a characteristically English failing to overlook branches of business not dealing with large quantities of staple commodities, and thus many of the smaller but remunerative industries have passed out of our hands. When one observes that almost every sheet of ordinary blue official paper is decolorised when accidentally brought into contact with an acid, betraying the fact at once that its colouring matter is ultramarine, one realises that a very considerable consumption for this and similar purposes must take place. Like most trades based upon chemical principles, the manufacture of ultramarine has recently made rapid strides, and some of the latest developments are recorded in a paper by J. Wunder, appearing in a recent number of the _Chemiker Zeitung_, which is worthy of some attention. With most people not directly interested in it, the term ultramarine is taken to mean the _blue_ pigment known under that name, the words being reckoned almost synonymous. Others, more erudite, recognise the existence of a green variety, but that the production of such colours as red and violet is possible is scarcely suspected. Of course the blue is the most important, but even that does not correspond to one specific substance, products of different shade being prepared by modifying the process of manufacture. As usually made, ultramarine is formed by heating together carbonate of soda, kaolin, sulphur, and charcoal, with limited access of air, the resulting pigment being green; this, on roasting with sulphur, becomes blue. If the operation be conducted with complete exclusion of air, so-called ultramarine white (in reality _grey_) is produced, which becomes green on further heating. Ultramarine blue capable of resisting the action of alum is sometimes required, and may be obtained by the use of a highly silicious charge and much sulphur, the burning being conducted in crucibles or in mass according to the purpose for which the pigment is required. The former process is costly, while the latter gives a product containing a good deal of free sulphur, which is objectionable for such purposes as calico printing. Removal of the excess of sulphur by heat or caustic soda is not feasible, as the colour suffers in either case, but a certain amount of success has attended experiments with sodium sulphide, the colour often brightening noticeably.