Clegg^s Apparatus for producing Coal Oas. 143 



" From the above statement it appears that, in additioji to a 

 coi'isideiable diminution in the amount of capital sunk, (the firit 

 cost of the new apparatus being much less than that of the old,) 

 there is in the new plan a saving of three-fourths of the annual 

 expenditure. The tar and ammoniacal liquor have in no instance 

 paid the expense of collecting and casks; I have, therefore, not 

 noticed them. I hope soon to be able to lay before the piibfi* 

 the exact difiference, in point of value, of the gas, by the tWO* 

 modes of operating : suffice it to say, at present, that where th* 

 gas, upon the old plan, sells for 155. per 1000 cubic feet, th* 

 gas produced upon the new plan is worth 205. at least, making 

 a difference in the annual rental, where 50,000 ciibid fetit Aft 

 sold daily, of 4562/. 10$. 



" The expense of producing ah equal quantity of light Vwth 

 oil gas (taking Messrs. Taylors' own statement, as given in the 

 Journal of Sciences and Arts, vol. vi. p. 108,) would amount to 

 the erwrmoiis sum of 19,010/. 85. 4d. To prevent discussion, I 

 have allowed, with Messrs. Taylor, that an equal volume of oil 

 gas will produce double the quantity of light of coal gas. 



" The annexed table points out the illuminating power of dif- 

 ferent gases, as well as the quantity of azote, sulphuretted hydro- 

 gen, and carbonic acid, formed, from which the injurious effects 

 of letting the coal remain so long in the retorts will be seen. 

 The only correct mode of ascertaining the illuminating power 

 of different gases, is by the quantity of oxygen condensed by a 

 given volume of inflammable gas, tint gas having the greatest 

 illuminating power whith condenses the greatest cjaantity of oxy- 

 gen. 



Table 

 Showing the Quality of (he Gas from common Coal, at differetii 



Periods oj the Distillation, likewise the illuminativg Power 



of Gas from Oak, dried Peal, Lamp Oil, Wax*, &c. 



i iioui''!} gas 



:i hours' ga3 . . , 



5 hours' g«.s . . . 



7 hours' gas . . . 



9 hours' gas 



Ga« from oak . . 



Oas from dried peat . 



(ias from CanncI coal 



Qat from lamp oil 



G«» from wax . . 



Olcfiant gM . . . 



100 in. of 

 impure gas. 



Sulp. 

 Hyd. 



100 measures of purified gas. 



Carb. 

 Acid. 



blef 

 Gas. 



Carb. 

 Hyd. 



yo 



91 

 .')4 



80 



Cons. 

 Oxy. 



164 

 163 

 132 

 120 

 112 

 f>i 

 6K 

 170 

 190 

 220 

 284 



Gives 

 Car.Acid. 



91 



93 



70 



64 



60 



33 



43 

 100. 

 124 

 137 

 179 



• From Df. Henry's {taper referred to ia a preceding note 



« Fiout 



