18 CHELTENHAM COLLEGE NATURAL HISTORY SOCIETY. 
pushed in till the lid is placed again over the mouth. This lid 
consisting of a large plate of iron, is screwed tightly in, and moist 
clay is smeared round the edges to block up all the small holes 
through which the gas could escape. 
The arrangements for separating the gas from the various 
liquid and gaseous impurities, which are simultaneously produced 
by the destructive distillation of the coal, are very perfect. The 
old hydraulic main is done away with, communication between the 
retort and the atmospheric condensers being shut off at will by 
means of a valve. 
The atmospheric condensers, scrubbers, washers, and purifiers 
were all visited, and explained. 
Last of all we adjourned to the testing room, a small room in 
which the quality of the gas is ascertained, by law it must reach a 
certain standard of illuminating power, and must not contain more 
than a certain percentage of sulphur inpurities. 
A very pleasant afternoon was brought to a close by a vote of 
thanks, proposed by Mr. Hichens, being given to Mr. Coombes for 
his kindness. 
On Wednesday, Oct. 29th, Mr. Hichens gave a lecture on 
“A Journey down a Coal Mine,” in the Big Classical. Mr. Hichens 
began by describing the plants of the Carboniferous age, the 
remains of which constitute the greater portion of our Coal: huge 
club mosses, mare’s tails, and tree ferns, with some pine trees 
allied to the Araucarian pine. The scene must have been some- 
what dull—forests and vegetable growths of vast extent, but 
of monotonous sameness, consisting of plants of but very few 
kinds, and without flowers. The animal life was of comparatively 
low type—birds, and the animals that suckle their young, had not 
yet appeared on the earth; the largest creature was the Labyrintho- 
dont, a gigantic frog ; there were true reptiles and many butterflies, 
cockroaches, and other insects. Scorpions with stings have been 
found so that there were, presumably, other creatures to be stung. 
Mr. Hichens then proceeded to trace the origin of the various 
strata seen in a vertical section through.a coal area. The 
underclay with its uncompressed root like Stigmara, is the soil in 
which the forest grew. The seam of Coal is the débris of that forest 
accumulated during long years, the roof of the Coal consisting of 
sandstone, shale, &c., was deposited after the vegetable matter—the 
future Coal seam—had sunk below the level of the neighbouring 
