1842.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



203 



of 2J to 2} cubic feet, gaining from 3 lb. to 5 lb. in weight by the process. 

 No result had been given of experiments with sleepers of foreign fir timber, 

 in which both exhaustion and pressure had been applied, but it appeared that 

 the Scotch fir sleepers weighing 100 lb. when kyaniied under exhaustion and 

 a pressure of 100 lb. to the inch, gained 33 per cent, in weight, which was 

 equal to 3 gallons of water being forced into less than 3 cubic feet of timber; 

 he thought that this difference could not be all due to exhaustion, but that it 

 must depend greatly upon the quality of the wood, because under a pressure 

 of 100 lb. to the inch, the air contained in a tubular substance (such as fir 

 timber) would all be compressed into about ^ of its natural bulk without 

 previous exhaustion, so that the difference between 5 lb. and 30 lb. forced 

 into a sleeper, could not, he thought, be all due to exhaustion, but must 

 depend upon other circumstances not explained in this paper. 



The President thought that the greater degree of absorption by the Scotch 

 fir might be accounted for by its open texture, whereas the foreign timber 

 was more compact and also contained more turpentine. It might also have 

 been wetter than the Scotch fir, which he believed had been the case. 



Mr. Taylor observed that hitherto the attention of the meeting had been 

 entirely directed to mechanical action, but that the chemical combination of 

 the corrosive sublimate with the albumen of the wood, was the point most 

 insisted upon by Kyan ; it was supposed to be similar to the operation of 

 tanning hides, in which the tannin of the bark combined with and saturated 

 the animal gelatin, which would not otherwise be permeable by the fluid in 

 which it was placed. 



Lieut. Oldfield suggested that if the timber when piled in the tank was 

 subjected to the action of heat at 212°, the moisture contained in the capillary 

 tubes would be expelled in the form of steam, and that on the admission of 

 the solution, tbe tubes would instantly be filled with it, because of the partial 

 vacuum formed in them. 



Mr. Colthurst observed with regard to the tests for ascertaining the amount 

 of saturation of the timber, that lie had tried all those described by Mr. 

 Lynde, and had not been able to discover the presence of mercury in the 

 heart of any of the timbers prepared for the Great Western Railway ; their 

 dimensions were 6 in. by 12 in. Dr. Faraday had, he believed, detected it 

 by the aid of the galvanic battery in the heart of a piece of timber 2 ft. 

 square, after simple immersion in the solution for fourteen days. 



Mr. Moss had tried many experiments as to the most delicate tests for 

 ascertaining the depth to which the mercury had penetrated : the most satis- 

 factory test was gold-leaf, as from its strong aflinity for mercury, the presence 

 of the latter was immediately detected. The mode of proceeding was to put 

 some fibres of the wood to be tested into a small test tube, mixed with a 

 portion of dry carbonate of soda ; then to place over, but not in contact with 

 it, a small piece of gold-leaf, and apply beat to the bottom of the tube. If 

 any mercury was present, in however small a quantity, the fumes would rise 

 and discolour the gold-leaf. 



Mr. W. Cubitt said that timber was at all times, more or less, charged with 

 moisture : he had found deals, supposed to be dry, lose 10 per cent, of their 

 weight from steam drying ; it was evident that the presence of moisture in 

 the pores of the wood must militate against the success of kyanizing by 

 simple immersion, unless it was continued for a very long period. In close 

 tanks, when exhaustion and pressure were resorted to, the moisture was 

 perhaps of less importance ; but still, if the sap was extracted, and the 

 timber previously dried, the process of kyanizing would be more efiicient. 



Mr. S. Seaward adopted Mr. Palmer's position, as to the almost impossi- 

 bility of forcing the solution through the capillary tubes of a long piece of 

 timber, the pressure being applied equally all over the surface : he believed 

 the present method of kyanizing to be very imperfect, and alluded to a num- 

 ber of sleepers so prepared for the West India Dock warehouses having been 

 recently discovered to be decayed. 



Mr. Martin confirmed this account of the decay of the sleepers : fifty out 

 of seventy were destroyed ; they had been prepared by simple immersion, 

 and had been down about five years. He had understood that some of the 

 wooden tanks in which the solution was kept at the Anti-Dry-Rot Company's 

 yard were decayed. 



Mr. C. May believed that the destruction of the tanks might have arisen 

 from the constant corrosive action of the mercury, and not from decay. The 

 capillary vessels of timber filled with air and sap, under exhaustion the air 

 would expand and drive before it a considerable portion of the sap and 

 moisture. In preparing tlie compressed trenails and wedges he used steam, 

 and found that the pores were opened by it. He suggested that steam should 

 be blown through the tanks until all the timber in them was raised to a cer- 

 tain temperature, and then by opening the communication with the reservoir 

 the solution would rush in and fill up the vacuum. 



Mr. Cowper believed that it was only necessary to bring the chlorine of 

 the corrosive sublimate and the albumen of the timber into contact, when 

 sufficiently dry, to insure the preservation of the wood. He had occasion to 

 try experiments with paper pulp, and was constantly annoyed by its decaying 

 — but the addition of a small quantity of chlorine had preserved it good for 

 two years, and he believed that it would continue unchanged. 



General Pasley confirmed the statement as to the increase of the specific 

 gravity of timber from long immersion at considerable depths. He had 

 found all the timber, except the mainmast, in the Uoyal George, at a depth 

 of about 90 ft., water-logged. The oak timber had increased on an average 

 more than 50 per cent, above its usual specific gravity. 

 Mr. F. Braithwaite remarked upon the doubt which appeared to exist 



among members as to the correctness of that part of Mr. Timperley's paper 

 where a sleeper containing 3 cubic feet of timber was reported to have in- 

 creased 30 lb. in weight. Mr. Braithwaite had made some experiments, the 

 results of which showed that a piece of Memel timber containing 533 cubic 

 inches, and weighing when dry 9 lb. became double its weight when subjected 

 to a pressure of about 320 lb. per square inch without previous exhaustion ; 

 the machine which he used not being provided with an air pump. A smaller 

 jiiece of American pine, containing 76 cubic inches, and weighing 1 lb. 7 oz. 

 increased in weight to 3 lb. under a similar pressure. This, he contended, 

 established the correctness of Mr. Timperley's Report. There appeared also 

 to be a misconception as to the amount of corrosive sublimate employed : 

 the paper states tliat J lb. was the quantity used for each load of timber of 

 50 cubic feet. He promised to make some further experiments, and report 

 them to a future meeting. 



Mr. Bull had prepared considerable quantities of boards for the Calder and 

 Hebble Navigation, by immersing them in the solution for two or three days, 

 which was about double the period allowed by the patentees. He had some 

 specimens of the boards, and in almost all of them there was an appearance of 

 decay in various stages. An oak board 1 inch think, kyanized in 1839, had 

 lain ever since upon the damp ground exposed to the air : the sap part was 

 entirely decayed, but the heart remained sound; fungus was, however, 

 growing upon it. Poplar boards, kyanized in 183S, 39, and 40, were all 

 partially decayed ; those which were not prepared, and had been exposed in 

 the same situation for the same period, showed, however, more symptoms of 

 decay. In preparing the timber he had always followed the instructions of 

 the patentees, and had tested the strength of the solution with the hydro- 

 meter, but had mixed up fresh solutiou even more frequently than was 

 supposed to be required. On dismantling one of the tanks for holding the 

 solution, he found the iron-work partially destroyed and enturely covered with 

 globules of mercury. 



llr. Thompson explained that the hydrometer was not a correct testing 

 instrument if any vegetable matter was present in the solution ; that the 

 tanks on the premises of the Anti-Dry-Rot Company were necessarily made 

 of unprepared timber ; that the bi-chloride of mercury in solution would 

 penetrate any length of timber, if the extremities of the sap vessels were 

 exposed to it's action, but that it would not penetrate laterally without pres- 

 sure ; it was not, therefore, surprising that a water-tight tank of unprepared 

 wood should decay on the outside, even if filled with the solution. With 

 regard to the strength of the solution, at first it was believed that 1 lb. of 

 corrosive sublimate to 20 gallons of water was sufficiently strong, and much 

 timber had been so prepared, but experience had since proved that the 

 strength of the mixture should not be less than 1 lb. to 15 gallons, 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. In a cubic foot of wood prepared under a pressure of 

 70 lb. per square inch, mercury had been found by the galvanic battery to 

 have penetrated to the heart. 



Mr. Home mentioned that a new process had been invented by Mr. Payne 

 for rendering timber proof against dry or wet rot, and the ravages of insects ; 

 for increasing its durability and tendering it incapable of combustion. The 

 mode of proceeding was to impregnate the wood with metallic oxides, alka- 

 lies, or earths, as might be required, and to decompose them in the interior 

 of the wood, forming new and insoluble compounds. 



Mr. Taylor drew the attention of the meeting to a Memoir on the Preser- 

 vation of Woods which had been read before the French Academy of Sciences 

 by Dr. Boucheric. It was argued, that all the changes in wood were attri- 

 butable to the soluble parts they contain, which cause fermentation and sub- 

 sequent decay, or serve as food for the worms that so rapidly penetrate even 

 the hardest woods. By analysis it was found that sound timbers contained 

 from three to seven per cent, of soluble matter, and the decayed and worm- 

 eaten, rarely more than one or two per cent. ; since therefore the soluble 

 matters of the wood were the causes of the changes it underwent, it became 

 necessary for its preservation, either to abstract these soluble parts, or to 

 render them insoluble, by introducing substances which should prevent their 

 fermenting. This might be done by many of the metallic salts or earthy 

 chlorides. Pyrolignite of iron was particularly recommended as being a very 

 effective substance and cheaper than coirosive sublimate. The process was, 

 to immerse the end of a tree, immediately after it was felled, in the solution 

 of metallic salt, when, the vital energies not having ceased, the fluid was 

 absorbed throughout all the pores of the tree, by a process which is termed 

 "aspiration." The fluid had been applied in bags, to the base of the trees 

 when in a horizontal position, or to one of the branches, or by boring holes 

 to the heart, a few branches and a tuft of leaves being always left at the top 

 of the principal stem. It was necessary to apply the process speedily after 

 felling the timber, as the vigour of the absorption was found to abate rapidly 

 after the first dav, and became scarcely perceptible aliout the tenth day, 

 whilst in dead wood, or where there was any accidental interruption of the 

 flow of the sap during growth, the " aspiration " entirely failed ; resinous 

 trees absorbed less of the fluid than any other. The ends proposed to be 

 attained by this process were chiefly— preserving from dry-rot; increasmg 

 the hardness and the elasticity ; preventing the usual changes of form or 

 splitting ; reducing the inflammability and giving various colours and odours,, 

 according to the nature of the fluid absorbed. 



Mr. Bethell remarked that the process described in Dr. Boucherie's pam- 

 phlet was identical with that patented by him July 11th 1838, two years 



