tract, after drying, evaporated. The oil which was left did not solidify even when left in a vacuum over sulphuric acid for five days; it was therefore dissolved in water and the solution saturated with hydrogen chloride, but the substance was reprecipitated as an oil, no crystals being formed. The steam distillate, which contained, as stated above, an insoluble oil, was made strongly alkaline, evaporated to dryness on the water bath, mixed with excess of concentrated hydrochloric acid, and extracted with ether. The oily product, which solidified partially on standing, was dissolved in water and saturated with hydrogen chloride; the crystalline substance which separated melted at 113-117°, but after repeated recrystallisations it had a constant melting point of 125-126°.

An analysis gave the following figures. 0.2303 gave 0.4639 CO, and 0·1643 H2O. CHO, requires C55-17; H

C = 54·94; H = 7·93. 8:04 per cent.

The substance is therefore without doubt cis-methylisopropylsuccinic acid.

It is remarkable that in this reaction the cis-acid alone should be produced; no trace of the trans-acid could be isolated, and it could hardly have been overlooked, as it usually separates with great ease, and is readily purified.

Action of Ethylic a-Bromisovalerate on the Sodium Derivative of Ethylic Methylmalonate in Xylene Solution.

As explained in the introduction, the object of this experiment was to determine whether, in xylene solution, the condensation between ethylic bromovalerate and ethylic methylmalonate might not proceed in a different manner from that in alcoholic solution, yielding derivatives of glutaric acid.

Fifteen grams of sodium in the form of powder* (molecular sodium) were suspended in about 400 c.c. of xylene and 117 grams of ethylic methylmalonate added; at the ordinary temperature the sodium dissolved only slowly, but, on slightly warming, a violent evolution of hydrogen took place, and the sodium derivative of ethylic methylmalonate separated as a pasty mass, in fact, the contents of the flask became so thick that more xylene had to be added. Ethylic a-bromisovalerate (141 grams) was then poured into the cooled solution, but no perceptible action occurred, although the sodium derivative dissolved in the mixture; the flask was therefore connected with a reflux condenser and heated to boiling on a sand bath for five hours, when sodium bromide separated in large quantities. * As obtained by melting the sodium under the xylene in a corked flask and shaking vigorously.

When cold, the product was mixed with water, the xylene solution separated, and the aqueous liquid extracted three times with small quantities of xylene. The combined extracts were dried with calcium chloride, and the xylene distilled off as far as possible under the ordinary pressure; as soon, however, as the thermometer began to rise rapidly, the residue was transferred to a smaller flask, and the frac tionation continued under diminished pressure (80 mm.); the chief fraction distilled at 200-210°, and weighed 71 grams, or 35 per cent. of the theoretical yield of pure ethylic salt.

Hydrolysis of the Ethylic Salt.-This ethereal salt was hydrolysed

by means of a 50 per cent. solution of sulphuric acid in the manner

described in the previous instance (p. 284); after 12 hours, all oil having disappeared, the product was distilled with steam.

The sulphuric acid solution, on cooling, deposited a large quantity of crystals, which melted indefinitely at 160-170°, but on twice recrys tallising from water, the melting point rose to 174-175°, and remained constant. The following figures were obtained on analysis, showing that the substance was trans-methylisopropylsuccinic acid.

0.2102

gave 0.4327 CO2 and 0·1512 H2O. C = 54.97; H = 7·99. CHO, requires C 5517; H = 8:04 per cent.

The filtrate from these crystals, on extraction with ether, &c., gave an oily residue, which, on standing, partially solidified; it was then spread on a porous plate, and the solid residue recrystallised from concentrated hydrochloric acid, when an acid was obtained melting sharply at 115-116°. This was evidently isopropylsuccinic acid,* since, on analysis, it yielded the following result.

0.2403 gave 0.4657 CO, and 0·1667 H2O. C = 53·07; H = 7·70. CH2O, requires C 5252; H = 7.52 per cent.

12

The Steam Distillate.-As in the previons experiment (p. 285) this was made strongly alkaline with potash, evaporated to dryness, concentrated hydrochloric acid then added in large excess, and the whole extracted with ether; in this way, a solid substance was obtained which melted roughly at 110-120°, and on recrystallising four times from concentrated hydrochloric acid, gave cis-methylisopropylsuccinic acid melting constantly at 125-126°.

0.1926 gave 0.3905 CO2 and 0.1388 H2O. C = 55·29; H = 8·01. CH1О requires C = 55·17; H = 8·04 per cent.

The quantities of these two acids melting at 126° and 175° respectively were about equal.

* The formation of this substance is obviously due to the presence of traces of ethylic malonate in the ethylic methylmalonate used.

Cis- and trans-methylisopropylsuccinic acids are therefore formed in about equal proportion by the action of ethylic a-bromisovalerate on the sodium compound of ethylic methylmalonate in xylene solution, whereas the same condensation conducted in alcoholic solution yields the cis-modification only.

XXVIII.—Available Potash and Phosphoric acid in
Soils.

By T. B. WOOD, M.A., Secretary to Cambridge and Counties
Agricultural Education Scheme.

Is a paper by Dr. Bernard Dyer (Trans., 1894, 115-167) a convenient method is given for determining the available minerals in soils.

Dr. Dyer determined the sap-acidity of the smaller roots of a great number of plants, and found that on the average the sap-acidity might be taken as equivalent to that of a citric acid solution containing 1 per cent. of the crystallised acid. He then determined, in different samples of soil, the percentages of potash and phosphoric acid soluble in a citric acid solution of the strength above mentioned. The samples were taken from the various plots in the permanent barley field at Rothamsted, and the analyses, thus conducted, indicated very satisfactorily the relative amounts of available potash and phosphoric acid in each plot, as evidenced by the known yield and manuring.

A determination of the percentage of potash and phosphoric acid soluble in a 1 per cent. citric acid solution, would thus appear to give a trustworthy and rapid indication of the amount of available potash or phosphoric acid in any soil.

For the last four years, I have taken part in the management of the experimental plots of the Norfolk Chamber of Agriculture, and of the Suffolk County Councils, and during that time I have come across most striking variations in the effects of potash and phosphatic manures on the different soils.

It seemed to me that an examination of these soils by Dyer's method might give important evidence as to its technical usefulness. The crops grown on the plots have included most of the ordinary agricultural crops, but for the purpose of this paper I quote only the results obtained with barley, in order that they may be more strictly comparable with those tabulated in Dr. Dyer's paper. The annexed table shows the average yield of several years' crops.

Table showing Yield of Barley in Bushels per Acre.

Higham. Warham. Bramford. Flitcham I. Flitcham II.

In each case the quantities used were as follows.

From this point of view these soils may be divided into two

groups.

I. Those to which the addition of potash produces only a small increase in the yield of corn—

Higham, Warham, Bramford..................

Average.
1 bushel per acre.

II. Those to which an equal addition of potash produces a very great increase in the yield of corn

Flitcham I.

45 bushels

Flitcham II.
22 bushels

Average.

33 bushels per acre.

The soils of Group I must evidently contain an abundance of readily available potash, whilst those of Group II must be deficient in this constituent in an available condition. Accordingly the soils of the first group should contain much potash soluble in 1 per cent.

citric acid, whilst those of the second group should contain but little potash soluble in that solvent.

I have obtained samples of all the soils through the kindness of members of the Norfolk Chamber and of the East and West Suffolk Technical Education Committees, to whom I now tender my best thanks.

The soils are all very similar, being light soils on chalk subsoil.

Analysis of the Soil.

The samples were air-dried, sifted, &c., and the moisture determined in the air-dried fine soil, which was then used for all the other determinations, the results being thus calculated on the dry soil. Nitrogen, organic matter, phosphoric acid, lime, potash soluble in hydrochloric acid were all determined by the ordinary methods; the hydrochloric acid used was a mixture of the strong acid with its own volume of water, 10 grams of the soil being boiled with 50 c.c. of the dilute acid for half an hour, evaporated nearly to dryness, and extracted with water. The potash soluble in 1 per cent. citric acid was determined exactly as directed in Dyer's paper. The results are appended in the annexed tables.

Higham. Warham. Bramford. Flitcham I. Flitcham II.

Table showing Increase produced by Soluble Potash Manure side by side with the amount of available Potash as shown by Solubility in 1 per cent. Citric acid.