﻿36 Canadian Record of Science. 



unconsumed carbon. Chieliy solid, they rarely show a 

 central, longitudinal channel. Sometimes they are full of 

 minute air bubbles which, as they come to the surface, 

 merge into minute but irregular fissures and air cavities, 

 such as we might suppose to be formed by air enclosed in 

 a solidifying mass. 



The most interesting aspect, however, is to be found in 

 the surface markings. These take of the form of 

 transverse, often forking stric^e, between which may be 

 seen small round pit-like markings, and it requires no very 

 critical inspection to convince one that all these markings 

 are extremely faithful casts of the various structural 

 features of the vessels within which the rods were found. 

 So complete, indeed, are these casts that the terminal 

 walls of the vessels in all their details may be observed. 



On the 9th of December a second lot of coal from 

 another furnace, was received from Prof. Donald. This 

 proved, upon investigation, to have been derived from 

 some species of oak. It was very light, but showed 

 numerous rods of silica, completely filling the various 

 vessels. In this, as in the former case, when the rods 

 projected into fissures, they were commonly fused into 

 bead-like terminations, or the whole were joined into a 

 more or less continuous mass. These masses were some- 

 times transparent, but more often of a greenish color, 

 strongly suggestive of slag. They conmionly assumed a 

 nodular form and usually had the aspect of being formed 

 in situ by fusion of the extremities where these latter 

 projected into fissures. 



The rods themselves were found to be white or glossy, 

 and transparent, rarely green, but often dark from the 

 inclusion of air or of particles of unconsujned charcoal. 

 They were found to measure from 37 //. to 249 ^. in 

 diameter, and thus to vary much more widely than those 

 from the elm, a fact which is quite in accord with 

 the different dimensions of the vessels in these two woods 



