The following résumé of the work so far published by the Home-grown Wheat Committee of the National Association of British and Irish Millers is based upon a paper presented by one of us to the International Convention of Millers which met in Paris during October, 1905. This work being well past the tentative and preliminary stages it proved possible to make a broad survey of it and to piece together isolated special portions which have been published from time to time.

In February 1905 I made a short communication to the Royal Society of London (Proceedings, Vol. Lxxiv. page 562), upon an apparent relation between the yield of wheat for England in the 21 successive years 1884 to 1904 and the aggregate rainfall for the three autumnal months (September, October, November) of the preceding years of the principal wheat-producing districts of Great Britain. The relation was put into the algebraical form:

DR Miller's interesting and important paper in the last number of this Journal (Vol. I. p. 377) raises several points in connexion with the long-continued action of rain on uncultivated and uncropped soils.

Some years before the appearance of Hellriegel and Wilfarth's work on the sources of nitrogen of leguminous plants, and while the part played by atmospheric nitrogen in the nutrition of crops was under active discussion, Berthelot was making some exact observations on the behaviour of uncropped soils towards the free element. He found that when 50 kilograms of air-dry arable soil were exposed to the air and rain in a vessel for seven months a great increase in the nitrogen content could be observed; the total nitrogen of the original soil had increased from 50 grams to 63, or a gain of over 25 per cent, after allowing for the small amount of combined nitrogen brought down by rain; in another experiment where the soil had first been washed free from nitrates, a gain of 46 per cent, of nitrogen was proved. In many other cases, however, the gain was only from 10–15 per cent, of the original nitrogen present in the soil.

It is now a well-established fact that the ammonia, which is formed in the cultivated soil by the breaking down of nitrogenous organic matter through the action of bacteria and moulds, is itself converted by oxidation into nitrates. The latter process, “nitrification“ proper, is effected in two stages by two distinct species of bacteria, the one carrying the oxidation to nitrite, and the other changing the latter compound into nitrate. It is also known that, in the absence of a base, nitrification does not take place. The most usual and most available soil base is calcium carbonate, which is, however, present in some arable soils to only a very small amount, less than ·05 per cent.; in such soils, and in others where its presence cannot be detected, nitrification is still active, a fact which seems to suggest that other substances may replace it and serve as bases for nitrification.

The purpose of the present paper is to give some account of experiments with oats, wheats, and barleys, carried out personally at St Andrews during the past five years.

An indirect method of estimating the heat value of food stuffs, such as milk, is to determine the amounts of fat, sugar, and proteid chemically, and to multiply by the average caloric value of each; but since the amounts of these substances themselves indicate the quality of the milk their calculated caloric value need not be employed as a test of its quality.

It is well known that at the beginning of the churning process a considerable volume of gas is evolved, necessitating some method of ventilation of the churn. In old-fashioned churns the gas was allowed to escape by simply withdrawing the cork or plug, while all modern churns have a special arrangement for the purpose. The gas set free has been stated to be carbon-dioxide, but hitherto no definite proof of its source or estimation of its amount has been recorded. It cannot very well be that the gas is formed by any chemical reaction at the time the churning process is going on. It seems more probable that it is produced by bacterial action during the ripening of the cream, held in a state of super-saturation by the liquid and released by the shaking in the churn in the presence of air. This view would account for the fact that it is only during the first hundred or so revolutions of the churn that any quantity of gas is evolved. It was with the object of demonstrating the correctness or otherwise of this latter theory that the following experiments were carried out.

One of the most popular and commonly used methods of preserving eggs is by means of water glass. Though this method was introduced only comparatively recently it has largely superseded older methods, and also appears to have led to much more frequent preservation of eggs on the small scale in households and by small traders. The method is simple and effective. The eggs are obtained when they are plentiful and cheap in spring and preserved for use during the winter months. It is therefore necessary to keep them for about six months. In the experiments described below some were left in a solution of water glass as long as four years.