326 
appearing, however, in an amorphous state, no crystalline form 
having yet been observed. In the breaking down of primary lava, 
magnetite is detached along with other substances and whether it 
be transported by various agencies or left in place, the soil arising 
from such lava usually contains magnetic oxide of iron. It is 
usually possible to make a separation of magnetite from other 
materials by the use of the magnet ; but this separation, however, 
seems almost impossible with Hawaiian soils or lava since the 
magnetite is so completely disseminated throughout the various 
deposits here and has not become crystallized out or separated 
from the matrix in which it was erupted. Whatever economic 
bearing this substance has on agriculture remains to be deter- 
mined. The oxide as such is of little importance to agriculture, 
though some of its compounds impart characteristic properties to 
the soil. The blueish color of certain newly plowed lands in va- 
rious places on Oahu indicates the presence of a hydrate of this 
oxide, the ferroso-ferric hydrate which in turn under certain con- 
ditions may give rise to a substance that is injurious to plant 
growth. 
NEW FARMERS' BULLETINS. 
Nuts and Their Uses as Food. By M. E. Jaffa, Professor of 
Nutrition, University of California. Prepared under the super- 
vision of the Office of Experiment Stations. Pp. 28, fig. 1. 
(Farmers' Bulletin 332.) 
This bulletin is a revision and extension of an article in the Yearbook 
of the Department for 1906, and embraces a description of several varieties 
of nuts, with statements as to their flavor, composition, digestibility, value 
as food, etc., with remarks on nut products, and suggestions for handling 
and marketing. 
Experiment Station Work, XLVIII. Compiled from the Pub- 
lications of the Agricultural Experiment Stations. Pp. 32, figs. 2. 
(Farmers' Bulletin 334.) 
Contents: Plant breeding on the farm — Sorghum for silage — Dry rot of 
corn — Starch from sweet potatoes — Profits from tomato growing — The 
keeping of apples — Weed seeds in manure — Weed seeds in feeding stuffs — 
Forage crops for pigs — Market classes and grades of horses and mules — 
Profitable and unprofitable cows — Blackhead in turkeys — Extraction of 
beeswax — An improved hog cot. 
Macadam Roads. By Austin B. Fletcher, Special Agent, Office 
of Public Roads. Pp. 39, figs. 10. (Farmers' Bulletin 338.) 
This bulletin is a revision of Bulletin 29 of the Office of Public Roads, 
and contains detailed information in regard to the construction, main- 
tenance and cost of Macadam roads, the kind and quality of stone, tools 
and machinery, labor and teams, etc.. with an appendix containing excerpts 
from specifications used in the construction of State-aid roads in Massa- 
chusetts. 
