We have next to consider a class of processes which are based primarily upon the action of an alkali, but which introduce the simultaneous action of a soluble sulphide, generally that of sodium. As far back as 1855 Jullion patented in this country a process of this nature, which, however, does not appear to have been applied to wood. The results obtained with such materials as straw and esparto appear to have been very unsatisfactory, and to have led to the early abandonment of the method. Recently the increased attention which has been given to wood as a raw material has led to a revival of these sulphide processes for its treatment. We believe that at least two processes of this class are being worked on the continent, viz. those of Dahl and Blitz. That of the former consists in heating wood, at pressures varying from 60–120 lb. per square inch, with a solution of the following composition:— Sodium sulphate 37 Sodium carbonate 8 Sodium hydrate 24 Sodium sulphide 28 Various compounds 3 ─── 100 {68} This solution is obtained only after the process has been some time at work, and it then remains tolerably constant. The wood, to commence with, is boiled with a solution containing a large quantity of sodium sulphate, with a small quantity of sodium hydrate, obtained by boiling sodium sulphate with lime. The liquor from this operation is then evaporated and calcined, the result being a fused mass which, when dissolved in water, yields a liquor containing the above-mentioned ingredients. The loss of chemicals is made up by the addition of fresh quantities of sodium sulphate. From experiments which the authors have made with this process, it appears, that while it is perfectly true that pulp can be obtained, it is necessary to employ either very strong solution or very high pressures. This is equivalent to saying that either the hydrolytic action is weak, or the tendencies to reversal of the hydrolysis are strong, and indeed both are to be predicted from the nature of the solution. One great objection to the process is that during the boiling a quantity of very foully-smelling compounds are produced. The process of Blitz consists in heating wood to from 50–60 lb. pressure, with a solution of sodium sulphide, containing an infinitesimal proportion of vanadate of ammonia. It is difficult to see what influence the presence of the costly vanadate of ammonia can have on the result. Actual experiment on this point has failed to convince us of its efficacy.