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condensable products are separated, and thence by the arch pipe H and connecting pipes to the gas holder, where it is stored, and when cool is ready to be used for heating or motive power, without any further treatment being necessary.

A gentle pulsation of the lead at C, and in the water at N and J, is an indication of successful gas making, and the quality of the gas can be roughly tested at the small tap in the arch pipe H.

To stop gas making turn off the oil tap and remove the oil cistern from its stand. Let the fire cool down gradually, keeping the furnace door closed about fifteen minutes. Shut the main cock leading to the gas holder. Then, before the lead sets, lift out the bonnet E, any residual gas being allowed to burn; and, when cool, the retort, bonnet, and standpipe can be examined and cleared out, if necessary, with a scraper.

In the United Kingdom the oils mostly used are the Scotch intermediate oils, so called because in flashing point and density they lie between burning oils and lubricating oils. This refuse of heavy paraffin from the Scotch distillers is of specific gravity 0.840 to 0.865, and lowest flashing point (close test) 235° F. or 105° C. The oil is inexplosive and free from offensive smell. The Mansfield apparatus makes 1,000 cubic feet of gas from 7 to 9 gallons of intermediate oil, which costs 51. per ton, or about 4 d. per gallon. The cost of fuel in the furnace comes to less than 1d. per 100 cubic feet of gas made (on a moderate scale), so that the total cost of fuel and mineral oil to make gas is about 6d. per 100 cubic feet.

Messrs. Crossley state that with their 12 H.P. NOM. engine the consumption of the Mansfield oil gas is 9 cubic feet per I.H.P. hour; and the total cost of fuel used by the combination of engine and oil gas plant with intermediate oil is about d. per I.H.P. hour.

It is stated that an engine developing 13 I.H.P. with ordinary coal gas will develop more than 17 I.H.P. with oil gas.

In Russia the black crude oil, worth 10s. per ton, yields 80 to 90 cubic feet of good lighting or motor gas per gallon.

Mansfield Sawdust Gas Apparatus

Fig. 194 is a sectional elevation, and fig. 195 a plan, of the Mansfield Sawdust Gas Apparatus, suitable for making gas from sawdust, shavings, wood débris, mineral, animal, and vegetable matter.

To make gas, the material for heating the retorts-by preference coke or coal-is introduced into the furnace, and the vegetable refuse to be operated upon is fed into the hoppers. The regulation of atmospheric air for the combustion of the heating fuel is effected by sliding doors. The heated gas from the furnace, in the form of carbon monoxide, passes from the furnace into the combustion chamber, where it meets a quantity of air, which passes in from the outside of the apparatus through regulated doors. The heated gas, on coming in contact with this supply of air, takes fire, afterwards passing over the partition walls, whence they emerge by a series of passages into the chimney flue, and so pass away to the outer atmosphere.

The following experiments have been made in the carbonization of mixed sawdust :

Gas made per ton of sawdust, not purified, but corrected for temperature and pressure=18,292 cubic feet;

Illuminating power of the gas, 4.73 candles;

Illuminating power of the gas after passing through lime hydrate, 15.61 candles.

Cost of Carbonizing Sawdust

1 ton of sawdust, producing 18,000 cubic feet

S. d.

of gas-say

20

Coke used to carbonize 1 ton of sawdust=560

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In addition to the large yield of gas, 1 ton of sawdust produces on an average 9.88 cwt. of pure powdered charcoal, for which a ready market should be found at about 30s. per

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ton. The gas has been tested with one of Messrs. Crossley's 4 H.P. NOM. engines, consuming 37.5 cubic feet of unpurified gas and 39.8 cubic feet of purified gas per B.H.P. hour.

Carbonization of Irish Bog

Irish bog carbonized 42 lbs.

=

Gas made=325.2 cubic feet corrected.

Time to carbonize 42 lbs. of bog=1 hour 55 minutes. Gas made per ton of bog=17,344 cubic feet corrected. The illuminating power of the gas after passing through a lime purifier on its way to the gas holder=12.06 candles.

The volume of gas was corrected to 60° Fahr. and 30 inches of mercury pressure.

The illuminating power of the gas was tested by Dr. Letheby's Photometer. A 'D' argand burner was used, having fifteen holes and a 7 chimney. The gas was corrected to 5 cubic feet per hour, and also for temperature and pressure.

CARBONIZATION OF SUNFLOWER SEED SHELLS

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Gas made per ton (corrected for temperature and pressure), 18,534 cubic feet.

Charcoal made per ton, 1.25 cwt.

In fine particles sulphuretted hydrogen was present in the gas at the outlet of condensers, and the gas was consequently passed through oxide of iron. No lime was used before passing the gas into the gasholder. The illuminating power of the gas corrected to 5 cubic feet per hour and for temperature and pressure. The gas was passed from the gasholder through a purifier filled with lime to free it from carbonic acid (CO2) ;

The unpurified gas is quite as good for driving gas engines as it is after purification by lime.

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