[3] For fuller information on this point, see the Author’s “Lectures on Agricultural Chemistry and Geology,” Part I.
[4] Since carbonic acid, as shewn in the previous chapter, consists only of carbon and oxygen, they retain the carbon and reject the oxygen.
[5] In malting barley, it is made to sprout a certain length, and the growth is then arrested by heating and drying it. Mashed barley, before sprouting, will not dissolve in water, but when sprouted, the whole of the starch (the flour) it contains dissolves readily by a gentle heat. The diastase formed during the germination effects this. By further heating in the brewer’s wort, this starch is converted into sugar as it is in the growing plant.
[6] For fuller and more precise explanations on these interesting topics, see the Author’s Lectures on Agricultural Chemistry and Geology, Part I.
[7] Potash, soda, lime, and magnesia, are compounds of the metals here named with oxygen. It is a very striking fact, that the suffocating gas chlorine, when combined with sodium, a metal which takes fire when placed upon water, should form the agreeable and necessary condiment, common salt.
[8] And occasionally do give; for a plump grain, and even a well-filled ear, are not unfrequently found where the straw is unusually deficient.
[9] [See pages 51 and 52], where these substances are described.
[10] A further portion, it will be recollected, is carried off in the cattle that are sent to market,—this is here neglected.
[11] Unless the soil happen to contain a large quantity of magnesia, which is rarely the case.
[12] That is, containing the same general proportions of sand, clay, lime, &c., or coloured red by similar quantities of oxide of iron.