. Electrical world. y varying proportions. The patents also refer too-xide of magnesium as a suitable component. Describing in the later patents the preparation of the material ofthe glowers, it is stated that the oxides to be used are thoroughlypulverized and intimately , and a plastic mass then made bythe use of a binder of clear starch. The water used in makingtiie paste should preferably be distilled to avoid the presence oflime, which, being mpre volatile than the oxides of the rare earths,its presence is undesirable. In another connection it is stated thatcertain of the rare earths
. Electrical world. y varying proportions. The patents also refer too-xide of magnesium as a suitable component. Describing in the later patents the preparation of the material ofthe glowers, it is stated that the oxides to be used are thoroughlypulverized and intimately , and a plastic mass then made bythe use of a binder of clear starch. The water used in makingtiie paste should preferably be distilled to avoid the presence oflime, which, being mpre volatile than the oxides of the rare earths,its presence is undesirable. In another connection it is stated thatcertain of the rare earths are inapplicable for the same plastic mass is then inserted in a press and forcedthrough a small hole of requisite diameter, this process being thesame as used in squirting incandescent lamp filaments. The rodsor threads thus produced are then allowed to dry, when they ac-quire sufficient strength to be conveniently handled. It is stated tobe desirable that the greatest specific gravity possible shall be. FIG. I.—A ROOM IN THE CHEMICAL DEPARTMENT. given to the material. In the process, that of heating, it isstated to be desirable for the heat to be gradually applied, but even-tually carried to an extremely high degree. Upon cooling, the rodsare ready to receive terminal connections. As previously stated, the processes at present employed in treat-ing the rare earths in their passage from the mineral form in whichthey are found to the state of glowers, are not given publicity. Ingeneral it can be said, however, that the processes involve chemicalskill of the most expert kind, and close attention to the minutestdetail. In particular, it is extremely necessary that all the chem-icals employed as reagents or otherwise shall be absolutely satisfactory results, the degree of heat applied during the treat-ing process must be exactly controlled, and also the concentration ofprecipitating solutions. Though organized for work on a large scale, a walk through
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
