In the official methods of soil analysis followed in this country, the available phosphate is determined by Dyer's (1) method. This consists in determining the amount of phosphoric acid, which becomes soluble, when 200 gm. of soil are shaken continuously for 24 hours with 2 litres of water, containing 20 gm. of citric acid. The result is expressed as a percentage of the weight of soil. It is usual to infer lack of available phosphate if less than 0·01 per cent. P2O5 becomes soluble under these conditions. Hall (2) has suggested the necessity for a revision of this limit.

1. The reaction between lime sulphur and acid lead arsenate is shown to be small and to have little effect on the chemical properties of either material as a spray.

2. It is shown that the oxidation of lime sulphur proceeds according to the empirical formula:

CaS.Sx + 30 = CaS2O3 + Sx-1

and that the calcium sulphides are hydrolysed in aqueous solution.

3. The addition of lead arsenate has no effect on the amount of sulphur precipitated from the lime sulphur by oxidation or by the action of carbondioxide.

4. Lead arsenate is only slightly decomposed by lime sulphur or by the oxidation products of lime sulphur, the main decomposition being due to the action of sulphuretted hydrogen formed by the hydrolysis of the calcium sulphides. This decomposition becomes marked in the presence of carbon dioxide which reacts on the calcium sulphide to form sulphuretted hydrogen.

5. The fungicidal value of the mixed spray—as judged by the mildew killing properties of the polysulphides—is not less than that of lime sulphur alone. Additional fungicidal properties may be expected from the presence in the spray of soluble arsenates and thioarsenates.

6. Judging by the chemical changes which take place in the mixed spray the insecticidal value of the lead arsenate would not appear to be greatly affected by the addition of lime sulphur.

7. There is an increased amount of soluble arsenic formed by the action of carbon dioxide on the mixed spray which may prove sufficient in amount to cause spray injury.

8. The A.O.A.C. method for the determination of sulphate sulphur in lime sulphur solutions is shown to be inaccurate. A method yielding more concordant results is proposed.

(1) The relationship between phosphate soluble in 2 per cent, citric acid and total phosphate present has been investigated in the following cases:

(a) Phosphates of known composition.

(b) Basic Slags.

(c) Mineral Phosphates.

(2) The relationship is best shown graphically and in nearly all the above cases is a straight line passing through the origin.

For each of three basic slags of widely differing citric solubility, the graphis a straight line showing that citric solubility is a definite constant, independent of the weight taken in the test, when allowance is made for a small constant error in the determination.

(3) The ratio soluble phosphate/total phosphate in the case of the mineral phosphates Gafsa, Ephos, Nauru, and a West Indian phosphate, depends on the weight taken in the test, the graphs are not straight lines.

A hydrogen electrode apparatus for soils is described. Similar or adjacent soils may show considerable differences in pH value, with no changes in their degrees of buffer action, as shown in titration curves with lime water. In such cases the conventional “lime requirements” are correlated with the pH values, but no such relation holds in dissimilar soils. The pH value of a soil suspension is intimately connected with the nature and amount of the cations present. Neutral salts markedly increase the hydrogen ion concentration of both acid and slightly alkaline soils. Sodium salts, including the hydroxide, give lower hydrogenion concentrations than the corresponding potassium or calcium salts, and chlorides give lower pH values than sulphates. The degree of buffer action (slope of titration curve) is unaffected by the addition of a neutral salt. Previous extraction of a soil with water causes a considerable increase i n the pH value of its suspensions. A number of soils showed a regular increase of about 0·1 in pH. value for twofold dilution. The “salt effect” and “dilution” effect appear to be of the same type. It is recommended that the soil-water ratio of 1:5 be generally adopted. The indicator methyl red gives erroneous pH values in turbid soil suspensions owing to the absorption of the red form, which is apparently a cation capable of undergoing “base exchange” with the soil.

1. The exchangeable Fe, Al, Ca, Mg, K, Na have been determined in twenty soils from different parts of the East of Scotland, by extraction with N NH4Cl solution. Data on pH, “Lime Requirement” and loss on ignition are given for the sake of comparison.

2. Only three soils were found to contain Fe and Al in exchangeable form.

3. The content of exchangeable bases varies from 5·6 to 22·2 milligram-equivalents per 100 gm. air-dried soil.

4. The evidence is insufficient to deduce any definite relationship between pH and “Lime Requirement” and the pH cannot be correlated with the content of exchangeable bases except in the case of soils similar in character.

5. It is suggested that the differences in the relative proportions of the exchangeable bases indicate that there are on the one hand fundamental differences due to soil type and on the other hand fluctuating differences due to manurial treatment.

6. Emphasis is laid on the fact that the degree of saturation of a soil is not necessarily indicated by the content of exchangeable bases. At present the absorptive capacities of the soils examined are not known.

7. Until a sufficient number of soils have been examined and classified, it is unlikely that any satisfactory generalisation on the subject of exchangeable bases will be forthcoming.

The Rothamsted Park Grass and Woburn Barley soils are almost all acid. Ammonium sulphate has caused a considerable increase in acidity, and sodium nitrate a slight decrease. Mineral manures have but little effect, and potassium sulphate has slightly increased trie acidity of the subsoil below the more acid plots. There is some evidence that the pH value 3·8 represents a maximum acidity in the Rothamsted soil. The change in pH value as a result of liming is less than that shown in the laboratory, owing in part to the subsoil acidity.

An account has been given of a digestion trial with sheep which was designed to assess the nutritive value of “sweet” rye grass and clover stack silage. The most noteworthy feature of the results was the appreciable depression of digestibility suffered by the crude protein of the crop as a result of ensilage. A tentative explanation of this effect has been put forward, based on a consideration of the high temperature attained in the stack.

In conclusion, the writer would like to state that the silage was made under the direction of his colleague, Arthur Amos, Esq., M.A., and to him thanks are due for permission to use the fodder for the purposes of the feeding trial. The writer also tenders his thanks to Mr G. Thurlbourn for considerable assistance in connection with the analytical work and the care of the animals.

Attention is drawn to the fact that there is variation, both morphological and physiological, within the aggregate of plants known as “white clover.” After a detailed study of some of the characters of the plant, it has been determined which of these are constant and which are alterable by external conditions.

The cyanogenetic behaviour has not been found correlated with any recognizable external feature of the plant, and has been found constant from year to year, and under different soil conditions. For this purpose, separate plants grown in pots and “clone” plants on various soils were used.

As a result of the study of distribution of cyanogenetic and acyanogenetic forms of white clover, it has been found that “positive” or “negative” plants give rise, under “open” conditions of pollination, to offspring approximately 75 per cent, of which are possessed of like cyanogenetic character.

The reactions of the unmanured and the limed and unlimed portions of the sulphate of ammonia plots on Eothamsted Park Grass and Woburn barley fields change steadily with increasing depth, and at 36 inches still show the same relations as in the surface soil. The difference in pH values between the limed and unlimed portions of the Rothamsted soil is substantially constant at all depths down to 36 inches. The reaction of the subsoil plays an important part in determining the effect of liming. The subsoils from the sulphate of ammonia plots at both centres are highly flocculated. Mixtures of 1 part of soil with 5 parts of water exhibit complete flocculation in the case of all samples below 9 inches and the velocity of sedimentation decreases and the volume of the final sediment increases regularly and markedly with the depth. Such changes in soil texture probably constitute important factors in the action of a high surface acidity.

(1) Removal of chlorine ions by soil from dilute hydrochloric acid solution has been shown to take place under the experimental conditions employed.

(2) Interaction between dilute acids and soil (free from carbonates) has been studied. The results show that hydrochloric acid, nitric acid, sulphuric acid, acetic acid, citric acid and phosphoric acid all react with soil. The state of equilibrium between the soil and the acid solution can be satisfactorily expressed by Freundlich's equation. The order of reactivity of the soil towards various acids does not follow any obvious rule.

(3) The various soil fractions do not show any fundamental difference in their equilibrium relationship with regard to an acid solution; the order of their power to react with acid following inversely the order of the size of particles in them.

(4) The experiments recorded seem to support the view that the interaction between soil and acids is a surface phenomenon.

1. The addition of casein to the mixed lime sulphur-lead arsenate spray causes:

(a) an increase in the amount of soluble arsenic formed on the decomposition of the spray,

(b) no change in the reactions of the polysulphide sulphur.

2. The addition of lime to the spray:

(a) decreases the formation of soluble arsenical compounds,

(b) reduces the fungicidal value of the spray owing to its reaction with the sulphur liberated from the calcium sulphide.

3. The addition of lime-casein to the mixed spray is influenced by the composition of the lime-casein.

If much free lime is present:

(a) the formation of soluble arsenic is dependent on external conditions which in certain cases tend to decrease the amount of soluble arsenic formed,

(b) the fungicidal value of the spray is reduced as in 2 (b).

If slight excess of lime is present, or if the sample has badly carbonated:

(a) the amount of soluble arsenic is increased,

(b) there is little effect on the reaction of the polysulphide sulphur.

4. The addition of gelatine to the spray:

(a) increases the formation of soluble arsenic,

(b) has no effect on the reaction of the calcium sulphide.

5. The rate of decomposition of the mixed spray is retarded by the addition of casein, lime, lime-casein and gelatine.

Much of the modern work on the physical properties of soil has been interpreted on a colloidal basis and more recently this hypothesis has been extended by the thermodynamical studies of Wilsdon and also by the investigations of two of us on an indirect measurement of the vapour pressure of capillary systems. There is evidence that the colloidal portion of the soil can be regarded as possessing a reticulate structure, possibly analogous to that shown by Zsigmondy to exist in silica gels. The pore space in soils is therefore an assemblage of voids and irregular capillaries ranging from ultramicroscopic dimensions in the colloidal portions to the macroscopic interstices between adjacent compound particles and the larger mineral fragments. Whereas in studies of evaporation and movement of water the total intersticial space is operative, the vapour pressure of soils at different moisture contents is very largely controlled by the minute pores associated with the colloidal portion and the larger voids have comparatively little influence. Vapour pressure measurements therefore afford a promising line of attack on the physical relations between the colloidal soil material and water, especially when the measurements are made on soils subjected to a variety of preliminary treatments, known to have a considerable effect on other physical properties. The effect of successive wetting and drying, heating and addition of salts are of especial interest in this connection.

It has long been recognised that in plants the susceptibility to disease is influenced to a considerable extent by the manuring practice followed. Ill-balanced fertiliser mixtures decrease the capacity for disease resistance; this has been frequently observed after the application of excessive amounts of nitrogenous manures, and has been demonstrated at Rothamsted and Woburn, where wheat and barley suffered most severely from rust and mildew in those plots which received excessive quantities of nitrogen; also at Cheshunt, where tomatoes heavily dressed with nitrogenous manures were readily attacked by disease-producing organisms. The effect of applying phosphoric acid has not, apparently, been clearly demonstrated, but it is generally assumed that, by favouring the development of a vigorous root system, its action is beneficial. Experiments at Cheshunt have shown that the use of manures from which potash has been omitted, produced a condition similar to that following the application of excessive amounts of nitrogenous fertiliser, and that the addition of potash tends to increase appreciably the ability of the plant to resist disease.

The variations in Hutchinson-MacLennan “lime requirement” with the amount of soil and calcium bicarbonate solution are shown to be connected with the buffer action of the soil. Indirect titration curves can be derived from the calcium bicarbonate results, and show a systematic divergence from the direct electrometric titration curves, owing to the variable calcium concentration of the final bicarbonate solutions. In the presence of calcium chloride both methods show lower pH values for a given base absorption and yield almost identical titration curves. The Hutchinson-MacLennan “lime requirement” is always less than the equivalent of the amount of calcium hydroxide necessary to give a neutral suspension in the electrometric titrations. The calcium bicarbonate solutions at equilibrium are always more acid than pH 6·2, but the “salt effect” tends to give results corresponding to a somewhat higher degree of neutralisation. “Lime requirements” should be obtained by interpolation to some arbitrary concentration, and an empirical relationship is given by which the interpolation may be made from a single determination. The Hutchinson-MacLennan method can give no indication of the intensity of soil acidity, but serves to estimate the amount of lime necessary to give a considerable reduction of acidity.

A résumé of the analytical methods hitherto employed for the chemical investigation of samples of silage has been given. It has been shown that these methods fail to yield trustworthy results when applied to the analysis of “sour” silage, owing to the disturbing effect of the presence of appreciable amounts of ammonium salts of organic acids in this type of silage.

Investigations have been made into the behaviour of the ammonium salts of acetic, butyric and lactic acids, when solutions of these substances, in the presence and absence of the free organic acids, are (1) submitted to distillation in steam, (2) evaporated in the steam oven under conditions comparable with those obtaining during the determination of the dry matter of silage. The bearing of these results on the problem of silage analysis has been discussed.

A modified analytical procedure for silage investigations has been devised which is capable of general application.

In a former paper (1) it was shown by solubility curves and pot experiments that the Wagner citric acid method is a satisfactory means of evaluating basic slags but is unsatisfactory for mineral phosphates.

1. A number of soils—treated with acid and washed free from it—have been found to possess in high degree the power of destroying phenol. Soils derived from certain geological formations seem to possess this property more than those derived from others.

2. This effect has been obtained from soils treated with sulphuric, hydrochloric, nitric, phosphoric, formic, and acetic acids.

3. The bulk of the loss of phenol is instantaneous; but the maximum loss is attained within about 20 hours.

4. An inverse relation seems to exist between the period of contact of acid with soil and the extent of the subsequent loss of phenol.

5. The loss of phenol is prevente d by several treatments—ignition of soil before or after acid-treatment; treatment with alkalis or sulphurous acid after acid-treatment; autoclaving the soil after acid-treatment and also in less degree before acid-treatment.

1. The value of lime-sulphur, liver of sulphur and ammonium polysulphide depending upon the amount of polysulphides that they contain, there is need for an exact method for the estimation of their content of polysulphide sulphur.

2. The method of R. M. Chapin has been tested under a variety of conditions and, after making slight modifications to increase rapidity and ease of manipulation, it is recommended as being sufficiently accurate for the purpose in view.

Part I. The changes in amount and composition of the mammary secretions of a heifer in its first pregnancy are recorded.

The most striking feature is the abrupt appearance at half-way through pregnancy of a viscous secretion consisting largely of globulin.

These results are extended to the primiparous and to the multiparous “dry” goat.

Colostrum is shown to be normal milk admixed with the globulin secretion.

The significance of the globulin is discussed. Reasons are advanced indicating that it may be an excretion of the cell when it changes from the growth phase to the secretory phase of life.

The stimulus to mammary growth is briefly discussed.

A partial analysis is given of the secretion from the tubercular udder of a cow. This secretion resembles somewhat the secretions of mid-pregnancy.

Part II. Instances are given of cases of premature lactation in the goat, and analyses are recorded of these secretions.

These cases are discussed in the light of Part I of this paper, and their bearing on the corpus luteum theory of mammary development is considered. The sexual precocity of the goat is such that the mammary growth may in all cases have been due to luteal influences.

A few cases of premature lactation in the cow are also reported.

The theory that the foetus produces a hormone inhibiting lactation is shown to be unnecessary.