452 



Mr. J. B. Hannay. 



[May 27, 



power of water was found to be determined by two conditions : 

 1st. Temperature or molecular vis viva ; and 2nd. Closeness of the 

 molecules on pressure, which seems to give penetrative power. From 

 these observations it will be seen that if a body has any solvent action 

 on another and does not act upon it chemically, such solvent action 

 may be indefinitely increased by indefinitely increasing the tempera- 

 ture and pressure of the solvent. In nature, the temperature has been 

 at one time higher than we can obtain artificially, and the pressure 

 obtained by a depth of 200 miles from the surface is greater than- can 

 be supported by any of the materials from which we can form vessels. 

 It will thus be seen that, whereas in nature almost unlimited solvent 

 power could be obtained, we are not as yet able to reproduce these 

 conditions artificially. Could pressure -alone increase solvent power 

 then much might be done, but pressure only acts by keeping the mole- 

 cules close together when they have great vis viva, and this latter is 

 only obtained by high temperature. 



As glass tubes were quite out of the question when a red heat and very 

 high pressure were required, iron tubes were resorted to, and a series 

 of attempts made to dissolve carbon by various gaseous solvents. The 

 difficulty of closing iron tubes as compared with glass tubes caused me 

 to try various methods, which I shall describe here. Tubes were made 

 of strong hydraulic tubing, 20" long, \" thick, and J" bore. These 

 were fitted with a plug, screwed with a strong screw fitting very well. 

 There was placed in the tube some powdered charcoal from which all 

 the inorganic matter had been removed by immersion in hydrochloric 

 and hydrofluoric acids and washing with water, and then sufficient 

 paraffin spirit to fill the tube two-thirds of its volume. The plug 

 was screwed in with a lute composed of silicate of soda and man- 

 ganese dioxide, but after heating the tube in a reverberatory fur- 

 nace for four hours it was found to be impossible to remove the plug, 

 so the end had to be bored out. There was neither liquid nor gas in 

 the tube, the luting having leaked. Another tube similarly filled was 

 fitted with a plug with a copper washer, the end of the tube, plug, 

 and washer being polished, but this also leaked and no result was 

 arrived at. Baryta, clay, asbestos, and other substances, wet with sili- 

 cate of soda, were all tried with the same result — leakage. A silver 

 washer kept comparatively tight, but only on one occasion. It was 

 thus seen that screw-closing would give no reliable results, so another 

 method was tried. A ball of iron, fitting the tube tightly, was placed 

 in it after the materials had been introduced. The end of the tube 

 was then narrowed by compression between rollers and turned smooth 

 inside. The iron ball was then drawn up by a wire attached and luted 

 by silicate of soda and fine manganese dioxide. It was expected that 

 the pressure would only serve to make the closing more secure, but, on 

 heating, the iron yielded and the ball was driven out with a loud 



