176 GOODYEAR ON GUM-ELASTIC. 



GAS BAGS. 



These are among the articles first made of the Mcintosh 

 fabrics, and which were commonly found to answer a good pur- 

 pose. They are now more cheaply manufactured, and answer 

 better when made of vulcanized gum-elastic plated fabrics or 

 elastic compound. 



They are made small for the laboratory, or of extra large 

 sizes for the conveyance of gas from one place to another. 



The value of the fabrics for this purpose is becoming well 

 known to chemists and others. 



GASOMETERS. 



A tank or reservoir is made of caoutchouc plated canvas for 

 holding gas in boats and buildings, where it is made on the 

 premises. They are made of the same form as a tub or bellows, 

 with a top of whalebone board, upon which weights may be 

 placed when required, or they are constructed like self-inflating 

 air-work. See plate , figs. 



HYBROSTATIC BELLOWS. 



The sides of these bellows are made of plated India rubber 

 canvas, in the common form, as represented plate , fig. , or 

 that of self-inflating air-work, which is preferable, as in fig. 

 The tops and bottoms are made of caoutchouc whalebone 

 board, to which the flexible parts or bellows of the instrument 

 are cemented ; consequently, nails are dispensed with in the 

 manufacture, while the seams are quite tight and strong, and 

 altogether the article is very superior to those which were 

 formerly made of other materials. 



