See BREWING (Encyc.), where a full account is given of Sir Robert Murray's method of malt-making, together with some valuable observations on malt by Mr Richardson of Hull. In a late edition of this latter gentleman's Theoretic Hints on Brewing, we are told, that Mr Edward Rigby of Norwich is of opinion, that the mere excitation of corn is not the only object obtainable by drying it on the kiln, but that some portion of the saccharine of malt is the effect of that process. "The operation of kiln drying the malt (says Mr Rigby) is as follows:—The grain is spread thick upon a floor made of flat bricks (tiles), or iron plates, which are full of perforations; immediately under this floor is the oven or furnace, in which is a large fire made of coals, cinders, or, in some places, billet wood; a current of air, at the mouth of the furnace, keeps up the combustion of the coals, and the air which is phlogisticated by their burning, and which, in a common fire place, rises up the chimney, passes, in this instance, through the apertures in the floor, and penetrates the whole stratum of malt before it can pass into the external air. Under these circumstances, it is evident, that the interstices of the malt must be filled with phlogistic air; and as the grain usually remains in this situation about two days, it is obvious, that if it have the power of absorbing phlogiston, it certainly must do it when long in contact with it. And that the malt does really imbibe some of this principle, is not only probable on the general ground of the truth of the preceding theory, but, I believe, it will be found, that the phlogisticated air which rises from the burning substances underneath, is corrected in passing through the malt; for without its being meliorated by this or some other cause, it is evident that the air in the kiln-chamber, more especially the lower strata of it, must be noxious, and probably even so much so as to be unfit for respiration and combustion. But to far from this being the case, I am informed, that workmen will lie and sleep many hours on the malt in this situation without suffering any inconvenience. And after mentioning this, it is scarcely necessary to add, that I find also, by experiment, that a candle will burn perfectly well in the air which is immediately on the surface of the malt.

Were heat alone sufficient for the purpose of completing the operation of malting, it certainly might be applied in a much more cheap way than is at present done; for the floor on which the grain is laid might, unquestionably, be heated equally without there being perforations in it, as with them. In which case, one kind of fuel would be as good as another; and, consequently, the present expense of previously burning the coals, to convert them into coals or cinders, might be saved.

But, admitting that the application of phlogiston to the malt, as well as heat, is requisite in this operation, the necessity of these perforations becomes evident, and also the propriety of previously burning the coals in such a way, that all the water, and those other heterogeneous particles which compose smoke and soot, may be dissipated; for these, merely as such, would obviously contribute little to the phlogistication of the malt, and would evidently impart some offensive flavour, if not some obnoxious quality to it.

Reasoning from the above premises (Mr Rigby concludes), it would seem, that as all the farinaceous parts of the barley are seldom dissolved in brewing, and the grains which are left have usually the disposition to become sour, thereby manifesting some of the acid principle to be still existing in them, it is not improbable that some further saccharine matter might be obtained from the grain by another exposure to phlogisticated air, or, in other words, by being once more laid on the kiln."

This is indeed so far from being improbable, that we think it must infallibly be the case. Sugar, it is well known, consists of oxygen, hydrogen, and carbon (see Chemistry in this Supplement, p. 466); but from the disposition of the grains to become sour, it is plain, that after the process of brewing they still retain much oxygen; and the azotic gas, which is here called phlogisticated air, there is every reason to believe contains both hydrogen and carbon. These, therefore, uniting with the oxygen of the grains, must make an addition to the saccharine matter. This has, indeed, been found to be the fact by Mr Richardson, who, in consequence of Mr Rigby's suggestion, was induced to brew a small brewing of malt, of ten quarters only, and stopping the process when, according to his general practice, one extract was full due, he ordered the grains to be laid upon one of his malt-kilns, and cinders to be applied the same as for drying of malt. This was continued for two days and a half, when the grains, being perfectly dried, were put into sacks, and, when cold, returned again into the mash-tun. The event, in some measure, justified Mr Rigby's Rigby's expectation; for the produce of fermentable matter was considerably more than he had reason to conclude would have been the case, had the extract been made in immediate succession, as it would have been in the ordinary course of his practice. He attempts, indeed, to account for it in a way very different from ours; but though we have the highest confidence in Mr Richardson as an experienced brewer, we must sometimes beg leave to think for ourselves as chemists. Like a man of sense, however, and a man of science, he says, "I am so well satisfied with the event of this experiment, that I shall probably be inclined, on some future occasion, to repeat it, in various stages of the process. The fine lively froth on the surface of the wort, in the underback, added to its transparency and good flavour, are circumstances which induce me to thank Mr Rigby for the hint, which, it is not improbable, may be applied to some useful purpose, in certain situations which sometimes occur in the brewing trade."