1880.] On the Artificial Formation of the Diamond. 453 



explosion. After trying several other methods of closing — outside 

 screwing and filling the mouth with molten metal on the top of a clay- 

 plug being amongst them — I came to the conclusion that nothing 

 would suffice but welding up the open end. This has been, when 

 carried out efficiently, invariably successful, and in all my later experi- 

 ments I have used it alone. It requires great skill on the part of the 

 workman, and it is only one man in a hundred who can perform the 

 operation with invariable success. The furnace used in these experi- 

 ments was a reverberatory one, 6 feet long (internal measurement) and 

 2 feet broad ; fire-place, 15 inches ; bridge, 9 inch.es ; hearth, 4 feet. 

 The roof sloped down towards the flue and the spent gases had exit at 

 the level of the hearth, thus carrying the flame down as it receded 

 from the fire, in order to have the hearth of one temperature. The 

 walls were 13 inches thick, and the roof formed of 4-inch fire-clay 

 covers. 



Three tubes, 20" x 1" X J" bore, were filled as follows : — 



No. I. 3 grms. sodium, J full paraffin spirit. 

 IT J. 



3 3 - tA » 3 3 3 3 3 5 5 3 3 



TTT -a. 



33 XXX. 3) 33 5 33 33 



On heating them in the reverberatory furnace, No. I exploded before 

 a visible red-heat had been obtained, so the temperature was not 

 allowed to rise any higher, and Nos. II and III allowed to lie for four 

 hours and then slowly cooled. On being bored open next day, No. II 

 contained a little scaly carbon, but No. Ill contained almost none, and 

 nearly all its liquid had been converted into gas, which rushed out on 

 boring it open. It was noticed by the workmen that the inside of the 

 tube was harder to bore than the outside, and I thought, as I found out 

 afterwards rightly, that the iron had been carbonised and converted 

 into steel. It seemed, then, that the free carbon had been taken up 

 by the iron. The same two tubes were welded up again, rather more 

 than half-full of liquid, and slowly heated, but before they came to as 

 high a temperature as they had been subjected to formerly, they ex- 

 ploded together. Two more were filled, welded, and heated, but again 

 they burst simultaneously. It appeared, then, that those tubes were 

 too weak, so two were made 20" X 2" X J" bore. On trying to weld them 

 when two-thirds full, the liquid got hot, and gave off enough vapour 

 to carbonise the white-hot plug and made a bad weld, so that they 

 had to be kept cool by trickling water upon them immediately below 

 the hot part. Several tubes were lost in closing before the workman 

 became deft enough at closing them. Two were at length obtained 

 well closed, and were heated, but again, before a red-heat was reached, 

 they exploded simultaneously, smashing the roof of the furnace. It 

 seemed on examining the tubes that one had gone off first, and struck 

 the other such a blow as caused it to burst, as one had a mark near the 



vol. xxx. 2 K 



