472 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



but the danger resulting from a leak in th'^ pipes is one 

 worthy of serious consideration. 1 A^ February 21, 1873, 86. 



EFFECT OF KUBBER TUBES ON ILLUMINATING GAS. 



The results of recent investigations by Zulkowsky show 

 that a diminution of intensity of the light, perceptible with- 

 out photometric aids, is produced by the 2:)assage of ordinary 

 illuminating gas through rubber tubes only* fourteen feet 

 long, and that this diminution is not due to mixture of air 

 by diffusion, but entirely to the partial absorption of some, 

 perhaps all, of the illuminating ingredients. Furthermore, 

 since these absorbed ingredients are given up in a vacuum, 

 and without doubt also gradually to the air, the effect of such 

 tubes is independent of the time they may have been in use. 

 3 (7, JSTovemher 18, 1872, 1128. 



IMPROVEMENT IN BUNSEN's GAS-LAMP. 



The Bunsen gas-lamp has been so modified by Professor 

 Finkener that the supply of gas, as well as of air, can be 

 regulated by the simple rotation of a ring on the foot of the 

 burner, and the non-luminous flame can consequently be di- 

 minished to any extent without liability to strike down. A 

 somewhat similar arranojement has lonG: been in use in ordi- 

 nary Argand burners. 



DURABLE COATING FOR LAMP-SHADES. 



The following mixture is suggested by Dr. Sels as a coating, 

 especially for lamp-shades, ceilings, etc., as j^i'eferable, in re- 

 spect to beauty, permanence, and cheapness, to ordinary oil- 

 paint, since it adheres firmly ; remains of a brilliant white at 

 high temperatures ; contains no organic matter ; and, by the 

 use of suitable mineral colors, can have any shade imparted 

 to it. Pure zinc white (oxide of zinc), thoroughly pulverized, 

 is added to a solution of silicate of soda of 40 to 50 Beaume, 

 until the mixture has the consistency of ordinary oil-paint. 

 The metallic surface to be coated must be thoroughly cleansed 

 (zinc and some other metals must be treated with hydro- 

 chloric acid), then washed with water, and the above mixture 

 laid on several times, by means of a brush, until the surface 

 is well covered. It will require but a short time between 

 the coatings to allow the previous one to dry. Too much of 



