A. B. Lyons — Composition of Hawaiian Soils. 42^ 



black sand can be separated by washing, consisting- of octo- 

 hedral crystals, part only of which are magnetic. Under a 

 lens, it will be seen that the crystals of chrysolite are studded 

 also with these iron crystals. 



The proportion of phosphoric acid in this soil (nearly three 

 per cent) seems fabulous ; what is remarkable is that it is much 

 higher than in any sample I have analyzed of the lapilli 

 whence it was derived. 



No. 2 is from a volcanic sand consisting of finer particles, 

 but more resistant to the action of acids, so that the residue on 

 treatment with hydrochloric acid is very large, and obviously 

 retains much base. The chrysolite in this soil is nearly trans- 

 parent, being scarcely at all oxidized. 



]^o. 3 is an older soil, but derived, I think, from a fine- 

 grained volcanic ash. There is almost no clay, but neither is 

 there much sand. The soil contains few particles exceeding 

 O'l™"" in diameter; more than half of it is "dust," the parti- 

 cles being less than .01™"' in diameter. Analysis indicates that 

 it is derived from a highly feldspathic lava. The figure for 

 phosphoric acid will excite incredulity in others as it did in 

 myself until confirmed by duplicate experiment. The quan- 

 tity varied greatly in samples of the soil taken from different 

 localities, but in all was absurdly high — much in excess of that 

 found in any sample of the country rock. 



The next four samples are derived from the decomposition 

 of comparatively recent lava. Most of the arable soil on 

 Hawaii and much of that on Maui belongs to this class. These 

 soils agree in containing, like those of the first class, much 

 unoxidized iron and a large proportion of phosphoric acid (in 

 no case amounting, however, to as much as one per cent). 

 The proportions of calcium and of potassium are generally 

 not very small, but vary greatly with the climate. When the 

 rainfall is not excessive, these bases are present in good, or 

 even in large, proportion ; but in rainy regions, as in the Hilo 

 district, they may be greatly reduced, especially the calcium, 

 as illustrated in sample No. 5 in the table. This same sample 

 is remarkable again for its small content of silica and for its 

 exceedingly large proportion of iron. 



The soils of the third class, designated ''old," are derived 

 from ancient lavas completely disintegrated. They are dis- 

 tinctly clayey, and of a deep red color, containing very little 

 ferrous iron. The proportion of phosphoric acid is generally 

 smaller than in the new soils and calcium is commonly low, 

 but these clayey soils are not as easily exhausted by careless 

 tillage as the others. 



Table No. II gives the results of analyses of a series of rep- 

 resentative Hawaiian lavas. No. 1 in this series is especially 

 interesting because it is from this material (lapilli) that the 



