U . S. B U R E A U
G A S - M A N T L E L I G H T I N G C O N D I T I O N S IN T E N LARGE C I T I E S IN T H E U N I T E D S T A T E S )
laBSTRACT.] FROM a careful inspection of about 4500 gas-mantle lamps in service in ten cities a summary of the condition of mantles, glassware, pilot light, and other particulars was made in order to determine to what extent the customer benefited through periodic ma,intenance service. By those observations it is found that a lamp not on regular maintenance is likely to be defective five and a half times as frequently as a lamp which is regularly maintained. Also, it is shown that, on the average, one in three of the lamps on regular maintenance was not in good condition, whereas the defects noted in the lamp,s not so maintained average more than one for every lamp. T H E D E T E R M I N A T I O N OF A B S O L U T E V I S C O S I T Y BY S H O R T TUBE VISCOSIMETERS. 2
[.~USTRaCT.] TifE Engler and the Saybolt Universal viscosimeters, which are the instruments usually employed in the oil trade, have such short outlet tubes that the equation for the flow through long capillary tubes is not applicable without correction factors. The literature has been carefully reviewed and further experimental work has been done. The conclusion is reached that water is not a suitable liquid for use in finding the relation between viscosity and time of discharge for short-tube viscosimeters, and that Ubbelohde's equation, and all others based upon it, are seriously in error. E F F E C T S OF H E A T ON C E L L U L O I D A N D S I M I L A R MATERIALS?
[A~STRACT.] A STUDY Of the behavior of celluloid and of pyroxylin plastics in general, when heated to different temperatures, corn* Communicated by Technologic P a p e r Technologic P a p e r 3 Technologic P a p e r
the Director. No. 99. No. ioo. No. 98.
VOL. I85, NO. I IOS--IO