Napier also describes in the Rabdologia two other larger rods to facilitate the extraction of square and cube FIG.
Cyanogen compounds also are present in the gas, and in large works, where the total quantity is sufficient, their extraction is effected for the production of either prussiate or cyanide of soda.
Its main features may be summed as follows: - a purely agricultural life, with the plantain, yam and manioc (the last two of American origin) as the staple food; cannibalism common; rectangular houses with ridged roofs; scar-tattooing; clothing of bark-cloth or palm-fibre; occasional chipping or extraction of upper incisors; bows with strings of cane, as the principal weapons, shields of wood or wickerwork; religion, a primitive form of fetishism with the belief that death is due to witchcraft; ordeals, secret societies, the use of masks and anthropomorphic figures, and wooden gongs.
In India at the present day there are thousands of small mills worked by hand, through which extraction the peasant cultivators pass their canes two or three at a time, squeezing them a little, and extracting per haps a fourth of their weight in juice, from which they make a substance resembling a dirty sweetmeat rather than sugar.
In deep mines the pillars may furnish the bulk of the product, and the control of the fall of the roof, so as to permit the successful extraction of the mineral, demands a well-schemed plan of operation.
The only practically available raw material for 'the extraction of uranium is pitchblende (q.v.).
Such calciners are used especially in roasting zinc blende into zinc oxide, and in the conversion of copper sulphides into chlorides in the wet extraction process.
The best results from extraction by diffusion have been obtained in Java, where there is an abundance of clear, good water; but in the Hawaiian Islands, and in Cuba and Demerara, diffusion has been abandoned on several well mounted estates and replaced by double and triple crushing; and it is not likely to be resorted to again, as the extra cost of working is not compensated by the slight increase of sugar produced.
It is also obtained in the action of potassium cyanide on gold in the presence of air, a reaction utilized in the MacArthur-Forrest process of gold extraction (see below).
Rather than a labour, for, by means of it, addition, subtraction, multiplication, division and even the extraction of roots are accomplished simply by the motion of counters.