of some Peculiar Forms of Coke. 17 



produces light vesicular masses, while the kind of which we 

 speak is very dense. It seems most probable that, when the 

 gaseous hydrocarbons evolved in the process of distillation 

 become more highly heated, they are decomposed and a depo- 

 sition of carbon takes place, as described by Dr. Percy in his 

 volume ' On Fuel,' 1875, p. 419. The Chinese give some of 

 their common earthenware a coating of carbon of this kind, 

 which gives it a metallic lustre. Mr. C. Tookey, formerly of 

 the Japan Mint, tells me that the Japanese use, for the roofs 

 of their houses, tiles which have been coated with carbon in a 

 manner similar to this. 



The second kind is that which is commonly known as hair- 

 like coke, and is interesting inasmuch as it presents, when 

 examined with the microscope, a great variety of curious forms. 

 In most instances these "hairs" are of a dull black; but some- 

 times they have a silvery appearance. The forms assumed are 

 occasionally of such a character that it is difficult to divest 

 one's mind of the idea that they are organic structures. 



The "hairs" are not uniform in thickness, but vary from 

 the Yo^-5- of an inch in diameter, or even less, to perhaps the 

 j-J-q of an inch, or even more. Some are straight or only 

 slightly curved (figs. 3, 4, 5) ; others are bent, distorted, and 

 knotted in a variety of ways. The finer "hairs " are mostly 

 smooth and cylindrical ; but some have a granular appearance ; 

 and occasionally the granules are so large in proportion to the 

 ize of the "hair" as to present an irregular knotted appear- 

 ance, like those forming the tuft of specimens such as fig. 10. 

 On many of the larger " hairs " more or less distinct transverse 

 markings may be seen (fig. 6) ; and these often become defi- 

 nite constrictions arranged in a very regular manner (fig. 7) — 

 so much so that they closely resemble, on a small scale, the 

 moniliform stems of the stone lilies or Encrinites, which are 

 so well known in the Wenlock and Carboniferous Limestones. 

 If one imagines a form such as this drawn out so as to increase 

 the distance between each ridge, the constrictions being at the 

 same time deepened, an appearance such as that given in fig. 8 

 would be produced. Forms like these are not at all rare. 

 Each segment appears to consist of a bundle of tubes or rods 

 close together where they spring from the segment below, but 

 gradually spreading out as they pass upwards, and terminating 

 abruptly at the rounded Surface which forms the top of the 

 segment (fig. 8 a ,*). No definite openings could be seen upon 

 the upper rounded surface ; but it appeared slightly granular. 

 This form reminds one strongly of certain kinds of tubular 

 Polyzoa, only that it is so much smaller. Fig. 9 represents 

 a form of which there are many varieties, all exhibiting a 



Phil Mag. S. 5. Vol. 1. No. 1. Jan. 1876. C 



