With some constituents longer time apparently leads to more thorough extraction, and with others to some re-adsorption, although the general effect of lengthening the time of contact and increasing the ration of water to soil will be to give somewhat higher results. In their methods, Messrs. Dunn and Simpson, respectively, employed three of water to one of soil, while the former analyst maintained contact for 48 hours and the latter for 24 hours. These are matters of choice, Variations which it is needless to discuss are also possible in the details of analysis subsequent to extraction.

In Table IV. of Appendix A, a comparative statement is given of the results obtained from the different analysts. To one accustomed to view such matters there is a measure of agreement between the figures which is eminently satisfactory, and reflects credit upon the care and skill with which the work was performed. In the table the results obtained from different analysts have also been averaged, and the figures thus obtained may claim to give such reliable information as is technically possible. In the averages for water-soluble salts and common salt useful figures supplied by the Government Laboratory have been included.

                                                                                              Discussion of results.

The principal results of the analytical work have been condensed in Table IV. (Appendix A). there are some interesting detail, however, in the return from the Geological Department (Table III., Appendix A) which merit attention. In this table the acids and bases found (upper division) have been calculated by a conventional method to show (middle division) what salts might be formed from them if the soil solution were evaporated to dryness. For technical purposes such a statement is often useful, and capable of direct application. For the present purpose it is less directly applicable, for the reason that the salts are harmful to crops only because dissolved in the soil water, and on solution the salts cease to exist as salts and become a potential mixture of bases and acids or to be more exact—a mixture of positive and negative ions.

another useful feature of the return from the Geological Department are the data for nitric acid and soda. That Department had been asked to determine those constituents in four samples only out of 40, it being assumed that excess of nitrates was not the probable source of trouble, and that soda would probably be the principal base of the salts. The Department however, determined those constituents in all of the samples submitted to it and it is now definitely shown that nitrates are not the harmful salts. It is also shown that soda is easily the predominant base in the salts, and in only three instances out of the 40 does the soda (which was directly estimated by Mr Simpson) not exceed in amount—and for the most part it greatly exceeds—all the other bases put together. The assumption that the soluble salts in these soils exist for the most part as potential salts of sodium is thus experimentally proved.

In discussing the chlorides, sulphates and carbonates in soils, it will be convenient to follow the American method, and refer them to a common standard, viz., the sodium salts. In following this course it is not forgotten that the presence of lime and magnesia will modify the effect of the salts stated as salts of sodium.

                                                                               Relative importance of the Salts found.

The soils of which independent analyses were obtained from different analysts were representative of three sets of conditions. One set represented soils at present under wheat, one set bush lands immediately adjacent to growing wheat, and one set represented different types of bush land of unknown character. The amounts of soluble salts in these three sets of soils are given in Tables 2, 3, and 4 following. The figures are the average results from the analysts, as shown in Table IV. (Appendix A), and include all depths of the soils.

                                                                                                 Lands under Crop.

these include sample 3 (Jackson's), sample 5 (Stewart's), and sample 13 (Kellerberrin crop). Soils 3 and 5 both carried successful wheat crops, but crop on 13, bordering a salt flat, was apparently affected by salt, although standing 30in. high.

                                                                                            TABLE 2.
                                                                                    Lands under Crop.

___________________________________________________________________________________________________ Sample. Total Inorganic Common Salt. Sod. Sulphate. Sod. Carbonate. Lime. Magnesia.

                                   Salts.   

___________________________________________________________________________________________________ 3 .. .. .. •277 •113 •146 •072 •0055 •0048 5 .. .. .. •230 •034 •215 •013 •0681 •0067 13 .. .. .. •437 •328 •048 •014 •0022 •0058 _____________________________________________________________________________________________________ Average .. .. •315 •158 •103 •033 •0253 •0058 Average 3 + 13 .. •357 •221 •047 •043 •0039 •0053 ____________________________________________________________________________________________________ The average of these soils indicates that common salt is the prominent salt, although the figures indicate a considerable amount of sulphates. It is evident, however, that this is due to the content of soil 5. Examination of the details of analysis shows that soil 5 is exceptional among all soils taken from the district, and the figures indicate the presence of gypsum at the third foot. No other soil contained one-fifth of the lime shown by this soil, and most of them about one-tenth. No other soil had so much sulphate. On this account a second average is made in Table 2, from which soil 5 is excluded. This calculation shows that chloride as common salt is certainly the important salt.

                                                                                          Bush Lands adjoining Crops.

These include samples taken in the bush, just outside growing crops, viz., No. 7 at Simpson's, No. 8 at Machen's, No. 9 at Shepherd's, No. 14 at Willis', and No. 20 opposite Thompson's crop. Where the samples were taken the soil was apparently similar to that of the adjoining paddock.

                                                                                                          TABLE 3.
                                                                                            Bush Lands next to Crops.

___________________________________________________________________________________________________ Sample. Total Inorganic Common Salt. Sod. Sulphate. Sod. Carbonate. Lime. Magnesia.

                                   Salts.   

___________________________________________________________________________________________________ 7 .. .. .. •132 •035 •008 •059 •0069 •0065 8 .. .. .. •490 •368 •062 •051 •0057 •0097 9 .. .. .. •605 •410 •095 •056 •0026 •0079 14 .. .. .. •367 •216 •026 •049 •0054 •0040 20 .. .. .. •446 •301 •052 •051 •0106 •0056 ____________________________________________________________________________________________________ Average .. .. •408 •266 •049 •053 •0062 •0067 ____________________________________________________________________________________________________