[28] Communicated by Mr. T. S. Peckston.
| Varieties of Coal. | Ratio of time in Decimals. |
|---|---|
| Scotch Splent or Cannel coal | 1,00 |
| Newcastle coal, (Nesham) | 1,04 |
| Gloucestershire coal | |
| Forest of Dean first variety (Low Delph) | 1,08 |
| Newcastle coal, | |
| Second variety, (Middle Delph) | 1,09 |
| Third variety, (Heaton Main) | 1,15 |
| Fourth variety, (Brown’s Wall’s End) | 1,18 |
| Fifth variety, (Hutton’s Low main) | 1,30 |
| Sixth variety, (Tyne Main) | 1,54 |
| Warwickshire coal, | |
| First variety, | 1,60 |
| Second variety, | 1,65 |
| Third variety, | 1,68 |
PART VII.
Horizontal Rotary Retorts, lately brought into use for manufacturing coal gas.
The many disadvantages attendant on the plan of decomposing coal in masses from five to ten inches in thickness, as already sufficiently exposed in the preceding parts, had naturally the effect of developing a principle of manufacturing coal gas, which practice has now fully established, namely: that to decompose coal, in thin layers from two to four inches in thickness, is to obtain the greatest quantity of gas from a given quantity of coal at the least expence.
Mr. Clegg was the first person who pointed out to the public the advantages that must accrue from this mode of operating, and to him we are indebted for the construction of an apparatus, the great ingenuity and superiority of which, entitles what is called the horizontal rotary retort, to all the merit and praise that belongs to the character of an original invention.
The numerous and great advantages of this distillatory apparatus, the rapidly increasing adoption of it,[29] and the almost certain prospect which exists of their ultimately superseding all former methods of decomposing coal, make it proper that I should lay before the reader, as full an account as my limits will permit, of the construction and operation of this retort, and the mode of applying it; and this becomes the more necessary on account of the many important improvements which the apparatus has undergone since its first adoption,[30] and of which no description has yet been laid before the public.
[29] Retorts of this description have been lately adopted, in the Gas Works at Bristol, Birmingham, Chester, Kidderminster, and at many other provincial Gas Establishments.