MECHANICS AND USEFUL ARTS. 51 



the rock, red, and black oak sills. Under a heavy pressure, varying from 

 10:;0 Ibs. to 1-500 Ibs. per square inch, working for about two minutes, the sap 

 for a few seconds would be ejected from the end of the sill; this would flow 

 sometimes in jets, like the discharges from the common garden watering- 

 pot, and at other times trickling in frothing exudations.^ It was found that 

 in white oak sills, under the enormous pressure of 1320 Ibs. per square inch, 

 the maximum gain in weight was 11 Ibs. per sill, or 3'S Ibs. per cubic foot. 

 In black oak, under 800 Ibs., the maximum gain was 17 Ibs. per sill, or 5'8 

 Ibs. per cubic foot. In red oak, under 1400 Ibs., the maximum gain in a sill 

 was 29 Ibs., or 9'6 Ibs. per cubic foot. In chestnut, under 1300 Ibs. per square 

 inch, the maximum gain in a sill was 13 Ibs., or 4'3 Ibs. per cubic foot. Upon 

 cutting the sills most successfully operated upon into thin cross sections of 

 two inches in thickness, they were found to be so fully saturated, that by 

 striking them violently against a board, the solutions would exude and cover 

 the surface with moisture. Though it required but two minutes in operating 

 the pump for the complete impregnation of the sills, yet the time occupied 

 in adjusting and removing the sill, and in filling and draining the cylinder, 

 amounted to eighteen minutes ; and the saturation of 25 sills was the average 

 work accomplished in ten hours. 



After a close analysis of the cost and details of the various systems, the 

 writer has been induced to select capillary attraction as the agent for intro- 

 ducing the solutions by the correct way shown to us by nature in the vegeta- 

 tive process, viz., by expelling and following the sap longitudinally, through 

 the pores and tubes of the timber. 



Preceded by a number of satisfactory experiments, the following plan has 

 been adopted : The sills are placed vertically, with but-ends down, in a tightly 

 caulked rectangular tank, 14 feet long, 5i feet wide, and 8 feet deep, built of 

 three-inch plank, supported by upright stays, and further secured by trans- 

 verse bolts, which prevent the sides from spreading. When the tank is 

 packed with sills, sufficient solution is added to fill it to the top of the sills. 

 In this simple apparatus, the pressure of a column 7 feet in height is thus 

 maintained at the but-end of a sill, the sap is expelled, and the preserv- 

 ing solution takes its place. A tank holding 100 sills will cost about $70, and 

 weighing when empty about two tons, can easily be transported. 



In order to ascertain the relative extent or degree of absorption of the 

 popular solutions by the different classes of timber, the writer caused to be 

 divided into three equal parts, a rock oak, a white oak, and hemlock sill; 

 each, as thus divided, was placed vertically in separate casks, which were 

 filled with the solutions. 



Cask with the chloride of zinc, one pound to 10 gallons of water, 

 blue vitriol, one pound to 12i gallons of water. 



the pyrolignite of irou (density riO-i), 1 part pyrolignite to 6 parts water. 

 After the duration of one week, 



The white-oak stick in the chloride of zinc, gained in weight, 6-8 per cent. 



blue vitriol, " 7'9 " 



pyrolignite of iron, " 1O7 " 



The rock stick in the chloride of zinc, " 4-8 " 



" " blue vitriol, " 4'6 " 



" pyrolignite of iron, " 5-6 



The hemlock stick in chloride of zinc, " 9-7 " 



" blue vitriol, " 10-1 " 



" " pyroliguite of iron, " 7'6 " 



