. Railway master mechanic [microform] . after a second heating of six hours no change in theconducting power is noted, the cover is considered in apermanent condition and is tested. Table T. gives the relative conductivity of the variouskinds of steam pipe cover tested up to April, 1S98. It-ives the results of the tests upon most of the samples ted, some being omitted when found to be of suchlow efficiency as to be of doubtful value. The conditions of testing were such as I haveadopted as being reasonably near the conditions of acrual practice. The room temperature was kept at 72degrees Fahren
. Railway master mechanic [microform] . after a second heating of six hours no change in theconducting power is noted, the cover is considered in apermanent condition and is tested. Table T. gives the relative conductivity of the variouskinds of steam pipe cover tested up to April, 1S98. It-ives the results of the tests upon most of the samples ted, some being omitted when found to be of suchlow efficiency as to be of doubtful value. The conditions of testing were such as I haveadopted as being reasonably near the conditions of acrual practice. The room temperature was kept at 72degrees Fahrenheit, and the openings into the roomwere carefully closed. Two specimens of each makewere tested, and in some cases, four, the mean valuebeing given m the table. Table II. gives the saving, in dollars, due to the useof the various covers Table III. shows that at th° end of ten years tinbest of the covers tested will have saved $40 more •From a paper presented at the June. 1S98, meetingof the American Society of Mechanical Fig. 1.—APPARATUS FOR TESTING BOILERCOVERING. than the poorest. The difference between the severalcovers of the better grade is exceedingly small. Themoney saving is computed on the following assumptions. Coal at $4 a ton evaporates ten pounds of wateiper pound of coal. The pipes are kept hot ten hours aday three hundred and ten days a year. Generallyspeaking a cover saves heat enough to pay for itself ina little less than a year, at 310 ten-hour days, and inabout four months at 365 twenty-four-hour days. It is evident that the decision as to the choice of covor must come from other considerations, as well asfrom the conductivity. The question of the ability of apipe cover to withstand the action of heat for a proonged period without being destroyed or rendered lessefficient is of vital importance. The increasing use otcork as an insulator has led to many questions as to itsability to remain fire proof. I have exposed it to atemperature corres
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