GAS, WOOD 611 



iron and the carbon, and the hydrogen is given off, carrying with it a small propor- 

 tion of carbon compounds. In this state it is valuable for heating purposes, but 

 possesses very little illuminating power, rather resembling, when kindled, the flame 

 of a Bunsen's burner. The various attempts which have been made to combine 

 volatile hydrocarbons with coal-gas, in order to increase its illuminating power, have 

 all failed on account of the speedy precipitation of the former ; but Mr. Euck claims 

 to have discovered that petroleum of the specific gravity stated will remain in com- 

 bination with the hydrogen. According to the report of Messrs. Quick and Spice, 

 the engineers concerned in the matter, this claim has been subjected to crucial tests, 

 and has withstood them all. The gas has been suddenly reduced in temperature from 

 60 to 30, has been kept for a month in a closed vessel, has been passed through 

 miles of iron pipes with many rectangular bends, without any consequent precipita- 

 tion. The illuminating power appears to be exceedingly good, and it is said that it 

 may be increased almost indefinitely by the removal of a small quantity of carbonic 

 acid by a simple process. The petroleum can be added to the gas at any point 

 between the manufactory and the burner, so that heating gas alone, it is proposed, 

 might be supplied from the mains, say to the kitchens or the conservatories of a largo 

 establishment, and the illuminating agent only added to that portion of the supply, 

 which was to be used for lighting purposes. The mode of manufacture ensures the 

 complete absence of the noxious sulphur- and ammonia-compounds with which we are 

 familiar, but the gas, although in this sense ' pure,' is not dangerously inodorous. It 

 has a distinct smell, pronounced by those interested in it to be agreeable, but which 

 is certainly sufficient to lead to the discovery of any domestic leakage, and thus to 

 obviate danger from explosions. 



At the present price of coal, the discovery of a source of gas which is as plen- 

 tiful as water, should manifestly have an important bearing on the cost of 

 production. The report of the engineers on this head is to the effect that they can 

 command millions of gallons of the petroleum spirit required, and that the illumi- 

 nating gas can be made at the cost of Is. 1\d. per thousand cubic feet. They say 

 also, that out of every thirty men required for the manufacture of coal-gas, twenty- 

 nine may be dispensed with in working Mr. Buck's process. These statements, if 

 borne out by larger experience, cannot fail to attract the attention of the companies. 



GAS, WOQSJ. Attempts were first made in France towards the close of the 

 last century to manufacture an illuminating gas from wood. The Thermo-lamp 

 of Lebon, a wood-gas apparatus, then and for some time afterwards excited con- 

 siderable attention, especially in the districts of Germany, Sweden, and Eussia, where 

 coals are scarce. This mode of illumination, proved however, to be a complete failure, 

 owing to the very feeble illuminating power of the gas produced, and as at this time 

 the production of gas from coal was rapidly becoming better known, anything like a 

 regular manufacture of wood-gas never in any case gained a footing. Subsequent 

 trials only confirmed the failure of Lebon, so that it was universally considered im- 

 possible to produce a practically useful gas from wood by the usual process of gas 

 manufacture. In the year 1849 Professor Pettenkofer of Munich had occasion to 

 repeat these experiments, and he found that the gases evolved from wood at the 

 temperature at which it carbonises consist almost entirely of carbonic acid, carbonic 

 oxide, and light carburetted hydrogen ; olefiant gas and the illuminating hydrocarbons 

 being entirely absent. Such gas was therefore totally unfit for illuminating 

 purposes. 



The temperature of boiling quicksilver, at which coal is not in the slightest degree 

 decomposed, is quite sufficient to carbonise wood completely. If small pieces of 

 wood be placed in a glass retort half filled with mercury and the latter be heated to 

 boiling, a black lustrous charcoal is left in the retort, whilst gas of the following com' 

 position is evolved : 



Carbonic acid . , . .'; . . 57'4 

 Carbonic oxide 36'6 



Light carburetted hydrogen . , : . . . . 7*0 



100-0 



If however the gases and vapours produced by the above experiment be heated to a 

 considerably higher temperature than that at which the wood is carbonised, Professor 

 Pettenkofer found that a very different result is obtained : the volume of permanent 

 gas is considerably augmented, whilst such an amount of illuminating hydrocarbons 

 is produced as to render the gas actually richer in these constituents than coal-gas. 

 Analysis of various samples of such superheated gas gave the following results : 



BK 2 



