[241] ‘Chambers’ Cyclopædia.’
The most commonly occurring tumour is the fatty one. It usually develops itself on the bodies of persons of from forty to fifty years of age. It seldom occasions inconvenience, and appears to be in no way prejudicial to health; occasionally, however, these tumours are very unsightly and unpleasant to look upon. The fat of which they are composed
appears to differ in no respect from ordinary human fat. The uterus is the principal seat of the fibro-cellular tumour. It occurs also in the scrotum, the bones and the subcutaneous tissue. These tumours sometimes attain great size, and grow very rapidly. They are sometimes met with exceeding 40 lbs. in weight. Certain polypi belong to this class of tumour.
A pseudo tumour is occasionally met within surgical practice, which may often be mistaken for a real one, by the unwary or inexperienced practitioner. This, which is known as a phantom tumour, appears to be caused by muscular contraction. Sir Jas. Paget, writing on this subject, says: “The abdominal muscles of hysterical women are most often affected, sometimes with intentional fraud. The imitation of a tumour may be so close as to require great tact for its detection; but chloroform, by relaxing the muscles, dissipates the swelling. Occasionally the apparent tumours move.
TUNG′STEN. W. Syn. Tungstenum. Wolframium, L. A heavy, grey, brittle metal, discovered by Delhuyart.
The word tungsten, in Swedish, signifies ‘heavy stone’ (tung-sten), the name being applied to the element because the source from which it is obtained is a heavy mineral called Wolfram. Wolfram may be regarded as a variable double tungstate of iron and manganese, and the tungsten occurs in this. A native tungstate of copper has been discovered in Chili. Tungsten is also found in the mineral scheelite, a tungstate of lime. From this latter compound it may be procured by digesting finely-powdered scheelite in hydrochloric acid. Chloride of calcium is formed, together with insoluble tungstic acid. Upon heating the acid to bright redness in a stream of hydrogen gas, the metal is left behind. When thus procured it is of a dark-grey colour, but under the burnisher it may be made to assume a metallic lustre. Metallic tungsten may also be obtained by the reduction of tungstic acid, by means of charcoal at a white heat. When procured by this method it is unaffected by hydrochloric or diluted sulphuric acid, although it becomes reconverted into tungstic by the action of nitric acid.
When tungsten occurs in the pulverulent form, it burns easily into tungstic anhydride, when heated in the air; and is oxidised and dissolved when boiled with the caustic alkalies or their carbonates in solution. An alloy, possessed of extreme hardness, may be procured when tungsten is combined with steel, in the proportion of 1 part of tungsten to 10 parts of steel.
There are two known oxides of tungsten, viz. a dioxide (WO2) and a trioxide (WO3). According to Wöhler there is a third oxide, having the composition (WO2WO3).
Dioxide, or Binoxide of Tungsten. (WO2.) This is an indifferent oxide, and is obtained by treating tungstic acid with hydrogen at a low
red heat. It occurs as a brown powder, which absorbs oxygen greedily from the air, and is dissolved by boiling with solution of caustic potash, hydrogen being evolved and potassium tungstate being formed.