NICKEL (symbol, Ni; equiv. 29-5— new system, 59—sp. gr. 8.8) is a grayish-white glistening metal, capable of receiving a high polish, of about the same hardness as iron, and, like that metal, malleable and ductile. It has about the same fusibility as wrought iron, but is less readily oxidized than that metal, since it remains unchanged for a long time in a moist atmosphere. and is very little attacked by dilute acids. It is strongly magnetic, but loses this property when heated to 600°. It dissolves in hydrochloric and dilute sulphuric acid with a development of hydrogen gas, and is very readily oxidized in nitric acid.
Nickel only occurs in the native state in meteoric stones, in which it is always present in association with the iron which forms the principal part of those masses. It is found in tolerable abundance in Saxony, Westphalia, Hungary, Sweden, etc., where it occurs in the form of kupfernickel (so called from its yellowish-red color), which is a combination of nickel and arsenic. The metal is obtained on the large scale for the purpose of mak ing German silver (q.v.) and other alloys, either from this compound or iTetss, which is an impure arsenio-sulphide of nickel, formed during the manufacture of swat (q.v.), by somewhat complicated chemical processes. In small quantities it may be obtained by reducing one of its oxides by means of hydrogen at a high temperature, or by exposing the oxalate to a very high temperature in a crucible lined with charcoal.
Nickel forms two compounds with oxygen—viz., a protoxide, NiO, and a sesquioxidc, which is not basic, and may be passed over without further notice:- The protaride occurs as a greenish-gray powder, which exhibits no magnetic properties, and is insoluble in water. It is obtained by heating the carbonate or the hydrated protoride in a closed crucible. The hydrated protoxide, NiO,HO, is obtained by precipitation from a solution of one of its salts by potash. The salts of the protoxide and their solutions are of a deli cate, very characteristic green color; but in the anhydrous state most of them are yellow. The neutral salts, soluble in water, slightly redden litmus, have a sweetish, astringent, metallic taste, and when administered in moderate doses excite vomiting. The most important of the salts is the sulphate Aq), which crystallizes in beautiful green rhombic prisms. It is obtained by dissolving the metal or its oxide in dilute sul phuric acid; and is the source from which the other salts of nickel, the carbonate, oxalate, etc., are obtained. The principal use of nickel is in the composition of various alloys, such as German silver (q.v.).
The sulphate of nickel has been prescribed successfully by professor Simpson in cases of severe headache.