Other persons seem to think that the laws of matter are different in the laboratory from what they are in the workshop; that the principles which regulate a scientific experiment are different from those which govern a large manufacturing process; but this is a wrong idea. The laws of matter are universal, substances have nearly the same properties in all places and in the hands of all men; water boils at the same temperature whether in the retort of a chemist, the saucepan of a kitchenmaid, or the pan of a soap-boiler; iron wire is as readily deprived of its rust in a chemist's acid bottle as in a wire-drawer's pickling tub; a piece of phosphorus will as readily ignite in the hands of a chemist as in those of a match maker; a galvanic battery yields the same quantity of electricity whether it be in the hands of an experimentalist or in those of a working electro-plater. It is true that many things which have appeared very promising in theory or in experiment, have {49} failed altogether in practice, but why is this? it is not that the principles of nature operated in the one case and did not operate in the other, but that we have imperfectly understood them, that from some unforeseen circumstances we have been unable to apply them; or that we have indolently abandoned them without sufficient or proper trial. In many cases we are unable to obtain the same conditions of success upon the large scale that we have upon the small one. In other cases a process fails because of its too great expense; many attempts have been made to supersede steam as a motive power by means of electro-magnetism, and engines driven by that force have been constructed of five or ten horse-power, but the cost of driving them has been found to be at least ten times the amount of that of the steam-engine of equal strength. And in other cases we fail because we attempt _at once_ to carry out upon a large scale that which has only been the subject of limited experiment, instead of enlarging the process by small degrees, and adapting the apparatus, the materials and the treatment, to the size of the operation. That also which appears very simple in the hands of an experimentalist, almost invariably becomes much more complex when carried into practice in a manufactory, simply because there is then a greater number of conditions to be fulfilled. Electro-plating a piece of steel with silver is to a chemist a very simple matter, because it is of no importance to him {50} whether the silver adheres firmly, is of good colour, or is deposited at a certain cost; but with a _manufacturer_ unless _all_ these conditions are fulfilled, the process is a failure. These matters, however, belong to invention and not to original discovery.