CHEMISTEY. 



growers consider the Delaware and the Clinton as 

 derived from the same wild variety, the Kiverside 

 grape (Vitis riparia, Mich.), which appears doubt- 

 ful, judging from the reaction with basic acetate of 

 lead; for the juice of the Delaware grape gives a 

 cream-colored precipitate, while that of the Clinton 

 produces a bluish-green one, indicating quite differ- 

 ent pigments in these varieties. 



An Economical Heating Gas. When steam 

 is passed over coke or charcoal at a red heat, 

 dissociation of the elements of the watery va- 

 por takes place, the hydrogen being set free, 

 and the oxygen forming compounds (carbonic 

 oxide and carbonic acid) with the carbon; 

 marsh gas is at the same time produced in 

 small quantity. The proportion of the gases 

 thus generated is, according to Frankland: 

 H, 56-9 ; CO, 29'3 ; CO 2 , 13-8. It is evident 

 that here we have a very important heating 

 gas, if it could be produced economically in 

 considerable quantities. How to do this ef- 

 fectually is the problem which has long en- 

 gaged the attention of chemists and gas-engi- 

 neers. This problem would appear to have 

 been solved a few years ago by Joshua Kidd, 

 an English inventor; and the improvements 

 -which have since been made on his process 

 justify the belief that a perfectly satisfactory 

 solution has been found of the question of a 

 cheap heating gas for domestic and manufac- 

 turing purposes. 



In Kidd's system perfected the generator consists 

 of a hollow cylindrical body or case of wrought or 

 cast iron. This is terminated below by a cast-iron 

 bottom, having a hole in its center about one half or 

 one third of its own diameter ; below this is a second 

 hollow cylinder of the same internal diameter as the 

 hole above it : in this lower cylinder the fire-grate is 

 lodged, the blast-pipe opening into it below the fire- 

 grate. When making gas, the bottom of the small 

 cylinder requires to be closed air-tight. This is ef- 

 fected either by means of a flat hinged plate, which 

 is kept tightly pressed against it by a heavily weight- 

 ed lever, or else by a short cap with a beveled edge 

 attached to it by a bayonet joint. In the upper and 

 larger cylinder there is a coil of thick wrought-iron 

 pipe which fits the cylinder pretty closely. The two 

 ends of the coil are turned outward at right angles, 

 and pass gas-tight through the body of the gen- 

 erator ; the lower end is connected with an arrange- 

 ment for supplying water under pressure, and the 

 upper end with a smaller steam-pipe passing down 

 parallel to the generator and terminating in a small 

 steam-tap in front. of the blast-pipe. In the center 

 of the top of the apparatus is a circular opening nine 

 inches in diameter, communicating below with a hol- 

 low inverted truncated cone projecting into the gen- 

 erator ; at the apex of the cone is a narrow cylindri- 

 cal ring, which serves as the seat for a heavy conical 

 valve. Above, this is surmounted by a short cylindri- 

 cal fuel-box, carrying at its upper end a hopper, the 

 opening between them being covered by a sliding 

 plate. Attached to the fuel-box is a short flue used 

 only when lighting the fire. Besides the central open- 

 ing in the cover, there are two smaller ones, viz., the 

 gas-outlet and a peep- or stoke-hole. 



If, now, a fire be lighted in the interior of 

 this machine, and water driven through the 

 coil, that water will be made to boil ; steam 

 will be produced which will accumulate in the 



Zer part of the coil, and, if not immediately 

 wed to escape, will become superheated. 



On opening the tap in front of the blast-pipe 

 this superheated steam passes down the small 

 pipe outside the generator, and blows with 

 considerable force into the blast-pipe, carry- 

 ing with it by induction a stream of air. In 

 this way the requisite oxygen to support com- 

 bustion and steam for decomposition are driven 

 into the apparatus, from which they issue as 

 a permanent gas To describe fully the sever- 

 al details of the working of the machine would 

 require more space than can be afforded here, 

 but the whole subject will be found treated in 

 extenso in the "Journal of the Society of 

 Arts," No. 1325. The chemical reactions which 

 occur in the generator are described as follows 

 by the author of the paper just quoted : 



Carbonic anhydride (C0 2 ) is doubtless first formed 

 by the action of the oxygen of the air upon the car- 

 bon of the fuel; this in its passage upward through 

 the heated fuel takes up another equivalent of car- 

 bon, becoming reduced to carbonic oxide, CO, thus, 

 C0 2 + C = 2CO, the nitrogen of course passing off 

 unchanged and serving only to dilute the gas. With 

 respect to the steam, this, as explained above, is de- 

 composed in its passage over the incandescent coal, 

 with the formation of hydrogen, carbon monoxide, 

 and carbonic anhydride. The latter in its upward 

 course shares the same fate as the C0 2 produced by 

 the action of the oxygen of the air, i. e., it takes up 

 another atom of C, and passes into the state of CO. 

 The decomposition of the steam, therefore, adds ma- 

 terially to the calorific va^ue of the gas, by enriching 

 it with hydrogen and a further quantity of CO. 



The composition of the gas produced by this 

 generator, when working at different pressures 

 of water, and with various kinds of fuel, has 

 been determined by analysis. The result is as 

 follows : 



As regards the quantity of mixed gases pro- 

 duced from a given quantity of fuel, this has 

 been ascertained experimentally with the fol- 

 lowing results : 



