Simple immersion being found imperfect as a means of injecting the sublimate, attempts were afterwards made to improve the efficiency of the solution by _forcing_ it into the wood. Closed tanks were substituted for the open ones, and forcing pumps, &c., were added to the apparatus. The pressure applied equalled 100 lb. on the square inch. With this arrangement a solution was made use of having 1 lb. of the sublimate to 2 gallons of water; and it was found that three-fourths of this quantity sufficed for preparing one load of timber. The timber was afterwards tested, and it was ascertained that the solution had penetrated to the heart of the logs. Mr. Thompson, the Secretary to Kyan’s Company, stated, in March, 1842, that experience had proved “that the strength of the mixture should not be less than 1 lb. of sublimate to 15 gallons of water; and he had never found any well-authenticated instance of timber decaying when it had been properly prepared at that strength.” As much as 1 in 9 was not unfrequently used. Kyan’s process is now but very rarely used; Messrs. Bethell, of King William Street, London, adopt it when requested by their customers. We have given the statements which have been made for and against this patent, but after a lapse of forty years it is difficult to reconcile conflicting statements. [Illustration: PATENT PRESERVATIVE SYSTEM. Horizontal Section of Mr. Kyan’s Original Tank and Cistern. A. _Bottom of Tank._ B. _¾″ Iron bolts to connect the planks which form the sides and end of the Tank and Cistern._ C. _The Cistern which contains the solution._ D. _The Tank._ E. _Pump for raising the solution from tank into Cistern._ F. _Tap for conveying the solution from Cistern to Tank._ G. _Wood sleepers to carry Tank and Cistern._]