460 



On the Artificial Formation of the Diamond. [May 27, 



first treatment. The carbon was now placed in the boat and a slow 

 current of oxygen started, then the bulbs connected and the current 

 made to pass through the platinum until all the diamond had been 

 burnt, when the current was stopped and the oxygen allowed to pass 

 for fifteen minutes more, when the bulbs were detached and weighed. 

 They were then reconnected and the gas passed for other ten minutes 

 to find whether all the carbonic acid had been expelled and reweighed. 

 They "weighed 0'2 mgrm. less than before. The numbers were as 

 follow : — 



Potash bulbs before combustion 43*8308 



„ after „ 43*8776 



. -0468 



Drying tube before combustion 264294 



„ after „ 26*4328 



— -0034 



•0502 



This gives a composition of 97*85 per cent, of carbon, which is a 

 pretty fair approximation to pure carbon. However, to determine 

 whether or not this was not the case, some further experiments were 

 tried. A small quantity of the carbon was placed on the platinum 

 boat and burnt in oxygen without any of the gas being allowed to pass 

 out of the apparatus, and the mixed gases so obtained transferred to a 

 eudiometer, and the carbonic acid and oxygen absorbed. It was then 

 found that a residue amounting to about 3 per cent, by volume of 

 the carbonic acid was left unabsorbed by alkaline pyrogallate solution. 

 This proved to be nitrogen. A blank experiment was done, but it 

 gave only a minute bubble of nitrogen. Another experiment was per- 

 formed with the following results : — 



Total volume 1837° 



After absorption of C0 3 148*5° C0 2 = 35*2 



After „ „ O 1*1° O 147*4 



N 1*1 



This plainly shows that nitrogen was present from some cause or 

 another, and as every precaution was taken in transferring the gas 

 from one vessel to another, and as the blank experiment showed 

 nothing, I am inclined to believe that the carbon, or at least some 

 portions of it, contained nitrogen chemically combined. The numbers 

 above given are degrees on the eudiometer tube, and are not more 

 than one-third of a cubic centimetre each. Their exact value was of 

 no consequence in the experiment, and the tube was only calibrated by 

 comparing one part with another, and not with an absolute measure. 



From the fact that no diamond was found when nitrogen compounds 



