September, 1924
INDUSTRIAL AND ENGINEERING CHEMISTRY
when the furnace wais not operating, indicated practically the same concentration of mercury. There was, moreover, a small blank correction from the reagents used in the analytical method. This blank was so small as not, to permit auy satisfactory estimate of its apparent mercury equivalent, and no correction on this account was inade in the results of these final tests. The results showed that, within t.he limits of accuracy of the methods of sampling and analysis used, no mercury was escaping from the high-frequency induction furnaces is operated during these final tests. A trace of mercury vapor may have been present in the laboratory air irrespective of whether the furnaces were operating or not, but any so present was probably considerably less than 0.035 mg. per cubic meter. The recommendation made by the U. S. Public Health Service in the final conolusion of its report” on the study of the old type of discharge gap is fully confirmed-namely, il
Turner. op. dl.. p. 341.
901
The problem of the prevention of mercurial poisoning in laboratories and industrial establishments can best be solved by enclosing all apparatus in which mercury is used and by conveyinp the fumes away from the worker’s face so that it will be impossible for him to inhale them.
CLE~NING AND REP.~IRING GAP-The fouling of the mercury in the hydrogen gap is very slight in comparison with the old type of alcoliol gap. The necessity of cleaning the mercury is thus practically eliminated. Replacements and repairs are required very infrequently. When, however, it does become necessary for any reason to open the mercury chambers of the gap, the furnace operator is protected from dust and vapors by the forced ventilation and the constant Aow of air into tlie compartment enclosing the gap. The furnace operator should wear rubber gloves at all times when handling parts of the mercury chambers of the gap. Thus the second source of danger of mercury poisoning which existed in the old form of discharge gap is reduced to a minimum in the present equipment.
By-product Coke Cell Structure’ By 0.0. Malleis T m K o ~ p e a COMPANY s L~aonrroarns,MBLLON INSTITUTE, PITTSHUAGX, PA
HE nature of the cell structure of coke has always been
T
considered an important property of coke. I n 1917, Ramsburg and SperrZshowed several pictures of cut longitudinal sections of cokes made from mixed coals regularly coked at different by-product coke plants throughout the United States. The relationship of cell structure to porosity data was studied and “standards for gaging cell structnre” were Drowsed. The nresent -uawer is a continuation oi the . earlie; work, except thxt the mesent study is confined to’ coke cell structure of unmixed coals or to mixed coals that are very similar. METHOD FOR PREPARINQ
COKESECTIONS The apparatus for cutting coke is shown by Fig. 1. The motor i s an ordinary dustproof:grinding type motor of ‘/e horsepower and 1750 r. p. m. The cutting wheel is known in the trade as an “elastic” cutting-off wheel (abrasive particles set in a bond of organic materials). The specifications for the wheel which have proved very satisfactory for cutting coke are:
j
Presented
“Coke Cell
under the title
Structure” before the
Section of Gar and Fuel at the G7th Meeting of the American Cliemicrl Society, Washinpton, D. C . . April 21 to28 1’324. * 1. Franklin Insi., 183, 391
