Upon examination it will be found, barley ears, and the new grain begins to form (being still in possession of its flower) about the same time with us as grapes do, in June; when we found the mean heat of the air in the shade to be 57.60 degrees.
Barleys in general are mowed from August to September; so that, in their growth, they are benefited by the whole of our summer’s heat, and for like reasons as in page 59, we estimate this 61.10 degrees: 3.50 degrees then would be the number of their constituent parts, taken from the degrees of heat in the shade, and which perhaps would be different if the actual sun-shine heat and what is reflected from the earth, were accounted for. Barleys are annuals, unbenefited by the whole of the autumn sun; but, after being mowed, they are stacked, retaining still much of their straw, leaves, and outward skins. In these heaps they heat, more or less, according to the condition in which they were housed; and which heat may reach to 120 degrees or more, but in general is equal, or somewhat superior, to that of our bodies. The properties of the grain, by this means improved, ripen, and from hence are more capable of preserving themselves. This might be a reason why a farther allowance should be made to the number of degrees denoting their constituent parts: how much, by a very great number of observations, made from the germination, ripening, to the stacking of the barley, in many years, and in many cases, might probably be ascertained; but the difficulty of doing this, and afterwards the impossibility of complying with the information such enquiries would afford, and the little need there is for it, as nature has allowed a considerable latitude for our deviating from what may be styled perfection, without any sensible injury: these circumstances render such enquiries unnecessary, if not fruitless.
Vegetables, but more particularly barley, from their first origin to such time as they might be ultimately separated by fire, may be divided into different periods, according to the distinct properties belonging to each, (and each of these require again a more exact enquiry.) Barley is under the act of germination, so long as the acrospire or stem is within the outward skin of the parent corn; this excluded, it vegetates so long as it receives nourishment by the interposition of its roots. It may be said to be in a state of concentration, when receiving but little or no support from the earth, yet it is acted upon by such heats as do not exceed what it might bear in the vegetative period; and in that of inaction, when, by the power of heat, it is placed in a passive state. Now malt is barley germinated, and, by a quick transition, is impressed with heats superior to those admitted in vegetation, and such as places the corn in a state of inaction. In the beginning of the process of malting, the more tenacious oils, together with some salts, are excluded from the body of the grain, to form the vessels requisite to forward the growth of the future plant. What remains in the parent grain (that choice food, at first necessary to the infant barley) are saccharine salts, alone applicable to the brewer’s purpose, and of the nature and quantity of which, he ought to be well acquainted. To retain these, and prevent a waste thereof, the germinated corn is placed in such heat, as destroys the union between its parts, from whence it becomes inactive. When this intent is obtained by the least heat capable of effecting it, the malt retains both its color, and the whole of its properties.
Vegetables, in no part of their growth, are ever affected by heats so great as to disperse their constituent parts; on the contrary, by natural heats, in general they are improved. The whole of their elements then, must be measured from the first degrees which form them, to the last which procure their highest perfection; and in climates where they are not benefited by the whole of such heat, their properties must be accounted only so many degrees, as in such places are between the extremes of their germination and maturation. Alike with malt, their whole number of constituent parts, denoted by degrees of heat, must be so many as are comprehended between that degree which leaves it in possession of the whole of their elements, and the first heat which excludes a part; for malt more dried than this, being less perfect, and losing some of its properties, fewer must remain.
The degree of heat which in malt divides the period of germination from that of inaction, we have found to be 119; the grain then is perfectly white, and shews little if any sign of effervescence; the first change, fire occasions therein, is to impress it with a light yellow color; this takes place at 129 degrees of heat, an alteration which can proceed from no other cause, but, in removing its original whiteness, to have expelled some of its primitive parts. The difference then between these two numbers of 10, specifies, in degrees of Fahrenheit’s scale, the number of properties constituting barley, malt.
It must be confessed this is establishing a principle of the art of brewing, upon the uncertain report of our senses, as perhaps our sight may deceive us in fixing this change of color exactly at 129 degrees; but we know white and black to be the two extremes of the dryness of malt, and that the middle color between them is brown, which being compounded of yellow and red, these four tinges, equally divided, as we have done in the foregoing tables, will corroborate our fixing the teint of yellow at this degree. The table shewing the tendency beers have to become fine, was formed from experiments made on brewings, whose governing medium heats were from 134 to 148, the proportion in point of time given by these, justifies the division between immediate pellucidity, at 119, and that taking place at two months, or 129 degrees. So from hence we may be satisfied, however an absolute perfection cannot be depended upon, yet this being the most exact division our senses afford, it approaches so near to truth, that if any mistake remains, it can be but trivial, compared to the latitude of errors, fermentation and time correct. But this number, 10 degrees, denoting the quantity of fermentable parts, must lessen in proportion as a continued, or a greater heat deprives the grain of more properties. A speedy spontaneous pellucidity is the effect of the whole fermentable parts; malt affected by heat, conveyed either through air or water, or through both, (so the medium of these exceeds not 138 degrees,) if assisted by the acids gained to the drink by long standing, such will obtain transparency. Beers, then, intended to be formed of themselves to become fine, in the calculations used to discover their elements, so many of the members of the constituent parts must be implied, as corresponds with the time the beer is intended to be kept; but when beers are made intentionally to require precipitation to become fine, in such proportion as we purpose to impress opacity on the drink, we must, in the calculations made to discover the temperature of the extracts, imply only so many of the constituent parts, as correspond to the medium heat which will occasion this foulness. These few observations shew the necessity of establishing this fundamental doctrine, the use of which will obviously appear in practice.
Thus does the success of this art depend on the instrument so often mentioned, which, by indicating the expansions caused by different heats, becomes a sure guide in our operations. I shall now close this account, by comparing with the principles here laid down, the defects which we, but too often, meet in barley when malted.