ASA ORVILLE A. DERBY 
most affected by the previous fracturing that the rock had suffered) 
were affected by this action, as is evidenced by the production of a 
crust of secondary minerals on the surface and in the cracks of the 
garnet and produced at its expense.t At a certain point on the 
surface of the granule here considered that was being attacked, 
certain ingredients contained to the point of supersaturation in the 
corroding solution commenced to separate out in a crystalline form, 
substituting the crust which at that point was being redissolved on 
its outer surface while its formation continued on the inner one. 
In front and around the growing crystal the solvent action of the 
solution on the garnet and the consequent formation of the crust 
became more active than elsewhere, thus lowering the original 
surface at that point and producing the bay-like indentation in 
which the crystal rests. 
All the hypotheses thus far presented for the genesis of the 
diamond are difficultly reconcilable with the known geological 
conditions of its occurrence as summarized, so far as regards those 
that are most essential, in my previous paper. Friedlander? has 
demonstrated experimentally that the diamond can be produced 
artificially by introducing solid carbon into fused olivine without 
artificial pressure and at a temperature (that afforded by the 
oxyhydrogen blowpipe) considerably below that thought indis- 
pensable by previous experimenters. We can therefore in our 
speculations on the subject eliminate altogether the element of 
pressure and, until the contrary is proven experimentally, admit 
hypothetically a still further extension downward of the range of 
temperature which, under varying conditions in other respects, will 
permit the crystallization of carbon in the form of diamond. 
In speculating on the genesis of the diamond we can therefore — 
put aside, at least hypothetically, the formidable ancient bugbear 
«In this case the dissolved material was redeposited zz situ. If we imagine that 
the material that, as may be presumed, was concurrently dissolved from the diopside 
was carried away (and perhaps with it a.certain portion of redissolved garnet crust), a 
plausible explanation is found for the much-discussed rounded form of these nodules. 
2 “Ferstellung von Diamanten in Silikaten entsprechend dem natiirlichen Vor- 
kommen im Kaplande,” Verh. d. Vereins z. Beférderung des Gewerbfleisses, February, 
1898, p. 45. 
3 A repetition of these experiments with other minerals, especially diopside and 
garnet, might give a very desirable addition to our knowledge of the subject. 
