70 REPORT — 1859. 



consists of a steam-boiler without reservoir, into which a very small quantity of vapour 

 is injected every second by means of a small hand-pump, or by a force borrowed from 

 the generator itself. This water, on descending through a serpentine tube, heated to 

 redness, becomes spontaneously reduced to vapour almost in a state of decomposition, 

 in which state the two gases, oxygen and hydrogen, are at the limit of combination 

 and separation. At the place where, and at the moment when this vapour, under a 

 pressure of from seven to eight atmospheres, is about to leave the serpentine tube, a 

 determinate and proportional quantity of mineral pitch, heavy pit oil (huile lourde de 

 houille), coal-tar, turpentine, or any other hydrocarburetted liquid is injected by a 

 contrivance exactly similar to that by which water was introduced into the boiler. 

 The superheated aqueous vapour and the hydrocarburet at the moment of contact 

 give rise to a series of decompositions and recompositions, into the theory of which 

 we shall not at present enter ; the result, however, is the transformation of all the gases 

 contained in the water and hydrocarburet into illuminating gas. 



This gas next passes into a purifier, where, at the same time, it becomes compressed 

 by several atmospheres ; on issuing from the purifier, it is collected in the usual manner 

 in a gasometer, whence it may be distributed at pleasure. 



M. Jacobi of St. Petersburg and M. 1' Abbe Moigno, who witnessed the experiment, 

 could at first scarcely believe the testimony of their own eyes, though they were 

 compelled ultimately to admit that the small apparatus just described generated per 

 minute almost 1500 litres (53 cubic feet) of very rich gas, which burned with mar- 

 vellous facility, and produced a very intense white light. We have here literally fire 

 and light extracted from water. 



By a simple calculation it may be shown that the quantity of heat contained, 

 theoretically, in the gas furnished by the above apparatus is many times greater than 

 the quantity in the charcoal burned in the furnace; so that if the generated gas were 

 conducted by suitable tubes into the furnace, the generation of gas might be prolonged 

 indefinitely, even though, at the same time, a notable quantity were reserved for ex- 

 ternal purposes of heating and illuminating. It is scarcely necessary to remark that 

 this is no case of perpetual motion, for the generation of gas only continues so long 

 as water is injected into the serpentine tube and a hydrocarburet through the orifice 

 of this tube. 



Now the water and the hydrocarburet possess the force stored up in the latent state, 

 and this force, in order to become vis viva, requires a mechanical effort which brings 

 together the vapour and the hydrocarburet. 



The illuminating gas thus pi-oduced, which is four times as rich as that used at 

 Paris, would not cost a centime per cubic metre (one-tenth of a penny per cubic yard) , 

 so that the method would introduce a vast improvement in the economic production 

 of light and heat. In applying the method on a large scale, it is true some difficulties 

 would have to be overcome ; the relative quantities of injected water and hydrocar- 

 buret would require to be determined experimentally for each hydrocarburet, and 

 kept perfectly constant during the process of alimentation. Again in transporting 

 the gas to a distance by means of pipes above or below ground, care would be neces- 

 sary in order to prevent decomposition and loss of carbon or richness ; but the experi- 

 ments already made to this end are perfectly satisfactory. 



On the Effects of different Manures on the Composition of the Mixed Herb- 

 age of Meadow-land. By J. B. Lawes, F.R.S., F.C.S., and J. H. Gil- 

 bert, Ph.D., F.C.S. 



Under what might be called the system of concentrated production, more prevalent 

 in this country than elsewhere, the arable land of a farm was, of course, subject to the 

 loss of those mineral constituents which were contained in the corn, and in the meat, 

 that were sold from it. Those of the straw of the corn-crops, and by far the larger 

 proportion of those of the rooh and green-excrps generally, were, for the most part, 

 returned to the arable land. But, in addition to this return, the meadow-land attached 

 to the arable farm frequently contributed to the manure applied to the rotation-crops. 

 Moreover, under the system of high farming, cattle-food, and also special or artificial 

 manures, containing certain mineral constituents, will be purchased, and thus enrich 

 the stores of the arable land. It thus happens, that the arable land, under good ordi- 



