235 



SCIENCE-GOSSIP. 



showed every gradation of colour from that of a 

 sun-dried road to a dirty ditch. A successful 

 erase ar tire raii'.vav s:a:i:r a::er Zr.::i',i •:_::.: 

 concluded our day's sport. 



7 iae I -aria ar ai Z aaar.iaai ii-arrtrs ::' r. . raia-aa, art 

 worth visiting. In the former (Pare Bordelais) 

 O. dispar seemed to be common, and if one can 

 judge by the immense damage done to the oak- 

 trees, the stag beetle (Lucanus census) must be 

 little short of a curse : from the size of the burrows 

 we were prepared for the giants we saw in the 

 Museum later on. In the Botanical Gardens 

 insects were very numerous, Macroglossa steUatarwa 

 and a large clear-wing hawk moth were dashing 

 about everywhere. The lepidoptera in the Museum 

 show cases are so many ghosts, the colours in 

 some species are entirely faded, and being for the 



most part unnamed and without locality, are of no 

 use for reference. Needless to say we found more 

 pleasure under the palms and magnolias outside. 

 Our stay in Bordeaux was very pleasant. We 

 returned home by boat, a trip which usually takes 

 from sixty to sixty-five hours ; in our case it occupied 

 three days and a half, having to lay-to on account of 

 fogs. The frequent soundings gave us an oppor- 

 tunity to secure micro material for the winter 

 evenings every time the lead was raised, so that 

 from a collector's standpoint, our trip was an all- 

 round success. We had filled our boxes, added to 

 Our knowledge, had no mishaps, been in much 

 pleasant company, and thoroughly enjoyed our- 

 selves. Yes, there is much to recommend collecting 

 ar -.viaeeis 



12, Lower Road, Rotlierititke, London, S E. 



BLACK DIAMONDS. 

 By James R. Gregory. 



/°\NE of the largest pieces of diamond ever 

 ^ discovered was recently exhibited at the 

 Academy of Sciences in Paris. It can hardly be 

 described as a diamond, being amorphous, and 

 having an indefinite form and no appearance of a 

 crystal. It is the variety named " carbonado," 

 and also known as black diamond. This specimen 

 had the enormous weight of 3,073 carats, or about 

 one and a quarter pounds avoirdupois, when 

 weighed immediately on being found ; but being in 

 sarr t aar.s slier.:".-/ rarers lis: abar: f: aaraas 

 •.vber "rrareb: :: Iia::_ra :\v;-;- ;; art evaparariar 

 of moisture. During twenty years' experience with 

 this scarce mineral, I have found it has a dark, 

 braavaaasb-biaa'-: aaiaaar, siaebaiv raiisbtr :r sara e cf 

 i:s aaaeriar srra'aaes ir btaaae ares'riv iaraiatr the 

 aaiaur is ::' ar a5r.tr erey ar sarrevaha: £a v.— aaiaur. 

 In texture it is generally uniform, in fact nearly 

 compact, though sometimes it is very slightly 

 cellular, similar in texture to a piece of spongy-like 

 lava. Some specimens have bright glistening specks 

 rhrarehart. thareh this v.-as r;: the aasa -.vi:h the 

 piece exhibited in Paris. 



This sararee raaiaaerai aaaars Lr are srr aii area ir 

 the Province of Bahia, in Brazil, and is found in 

 irreeriar areriar pieces eiehaire frarr haif a aara: 

 to frequently 200 or 300 carats each. Very rarely 

 srrali raaraeai perries a: the aaraaraaa art faara 

 with a more or less dull surface, which is all the 

 more remarkable in so hard a substance, as these 

 pebbles have been, undoubtedly, rounded by 

 attrition ; but how and by what material is a 

 moot point, as no other substance is nearly so 

 hard, or capable of rounding one of the 

 hardest and toughest materials in nature. There 

 cannot be a large quantity of the carbonado, or 



in sufficient quantity for detached pieces to grind 

 each other, as but a comparatively small amount 

 is obtained, possibly 50,000 carats would represent 

 a total of the annual production. This singular 

 substance is in considerable demand, and is 

 to an extent largely employed, I might say 

 almost the whole of it, for drilling hard rocks in 

 prospecting for gold, and other underground boring 

 work by means of the diamond drill. It is also used 

 far airiiiiaae raits :ar riaa:ir^ arai a:iatr rrraa ;aes ex- 

 tensive w a rkings ar a rear borings have been carried 

 a- with art air of aiaais singularly hard mineral. 



In composition it is pure, or nearly pure, carbon, 

 its impurity being probably a small percentage of 

 ] dde a: rar ; i; 'r urns ir oxygen with little or no 

 residue, and is converted into carbonic acid gas. 

 Its density is slightly higher than the ordinary 

 crystallized diamonds. As to its mode of origin, 

 nothing seems to be known ; no speculation on 

 that subject, so far as I know, has ever appeared. 

 It is exceedingly tough, and will stand an extra- 

 ordinary amount of grinding pressure, and its 

 lasting power is enormous, as after working in 

 hard rocks for many hours, or even days, the edges 

 and surfaces are hardly abraded. 



It is somewhat remarkable that this form of 

 diamond has not, up to the present time, been 

 discovered at any other district in which diamonds 

 have been found, and even in Brazil it occurs only 

 in the Bahia provinces, where it was first found 

 nearly a hundred years ago, when its value was 

 quite trivial — only a few shillings an ounce — while 

 at the present time it runs up to pounds sterling 

 per carat, exceeding the ordinary average price of 

 rarer aiiaraaraia taata: :r aeriair selected stcres. 

 i„ Kelso Place, Kensington ; December, 1856. 



