March 1, 1917.] 



THE INDIA RUBBER WORLD 



323 



which is condensed and flows on the water through the connect- 

 ing pipe to a receptacle on the right where the condensed sol- 

 vent is separated and drawn olT. 



The finishing operation of standard sheets consists in apply- 

 ing a cover coating of a colored rubber solution to both sides 

 of the sheets and passing them between the rolls of a two-roll 



NEW USES OF SPONGE RUBBER. 



Fig. 3. — Solvent Recovery Ai'I'.\ratus. 



vertical calender. Klingerit boards of different gage are made 

 on the same machine by doubling sheets of predetermined thick- 

 ness. 



It frequently occurs that the sheets made on the rolling ma- 

 chine or calender are spotted wilJi dark stains or imperfectly 

 laminated. The macliine shown in Figue 4 was therefore de- 

 signed and found very satisfactory in turning out perfectly 

 finished boards. 



It comprises two solid side frames supporting between them 

 a heavy bed-plate or table on which the sheets are placed. A 

 heavy polished, chilled iron roller is journaled in a movable 

 carriage that traverses the table in both directions, driven by 

 a reversible lead screw, the movement of which is controlled by 

 straight and crossed belt-driven pulleys. A sheet is placed on 

 the table and the weighted roller is passed back ajid forward 

 over the surface several times. It is then turned in a horizontal 

 plane and the rolling continued, after which the sheet is re- 

 versed and the other side treated in the same manner. 



Standard Klingerit "boards are 3.75 millimeters (about Vs 

 inch) in thickness, being built up with 15 thin layers that are 

 25 millimeters thick. They are blue, reddish-brown, or green in 

 color and the dimensions are as follows : 



Millimeters. 



2000 X 2000 



250O X 2500 



2000 X 3000 



3000 X 3000 



1250 X 4000 



160O X 6200 



Equivalent Inches. 



78.7 X 78.7 



98.4 X 98.4 



87.7 X 118 



118 X 118 



49.2 X 157.4 



62.9 X 244 



"It" material is made only in unvulcanized sheets from which 

 the various shaped packings are cut or stamped, the contained 

 rubber being vulcanized after the joint has been made by the 

 heat of the steam. For special purposes metal gauze or tin-foil 

 is placed between the sheets or they may be coated with graphite, 

 the object being to prevent vulcanization. Attention is particu- 



FiG. 4. — Arndt's Sheet .Rolling Machine. 



larly called to the fact that Klingerit packings should be kept in 

 a cool dry place, otherwise they will become hard and lose their 

 flexibility. 



DECAUSE of its cellular structure, sponge rubber has several 

 '-' very peculiar properties. For example, it has the lowest ap- 

 parent specific gravity of all solid bodies, being around 0.05. In 

 spite of its cellular structure it is water-tight, and very nearly 

 gas-tight. While it is honeycombed with minute cells, each cell 

 is an individual unit and the rate of diffusion of gases through 

 it is comparatively low. Because of its low specific gravity it has 

 a very low specific volume, which thus brings its cost within 

 range for common purposes. Perhaps one of the most important 

 uses to which it has been put is in the preparation of life pre- 

 servers. It will not waterlog, is light, conforms easily to the 

 lines of the body, and is not to be ruined by a pin prick. A life 

 raft made with sponge rubber is as near fool-proof as one can be. 

 Buoys, markers, etc., may be improved by its use. 



For some time the brains and time of many men have been 

 occupied in a search for a substitute or modification of the 

 pneumatic tire for automobiles. We have seen about everything, 

 from metal springs to tires made with the regular tire casing 

 but containing a solid block of gum used as a bumper. The 

 season of tire fillers occupies now only a page in the history of 

 this search. Springs have been discarded because of their slow-' 

 ness to respond, and it has been decided by the great majority 

 of automobile owners that nothing rides as easy as air, and 

 rather than use tire fillers they would substitute solid tires. 



Two serious objections to most tire fillers are that under con- 

 stant running they tend to heat up, and finally to decompose, 

 and, second, there is quite a tendency to form flat spots. 



As lias been mentioned, the most satisfactory tire filler to 

 date is air. This air is customaril3' held in an inner tube under 

 moderate pressure. It is now proposed to use sponge rubber 

 molded to fit the inside of the tire casing, and in this manner 

 produce a puncture-proof tire. The car still rides on air, but 

 this air is confined in innumerable little sacks. The c6nditions 

 necessary for a satisfactory tire filler are as follows : 



1. It must be quite stable and so constructed that fatigue 

 is reduced to a minimum. 2. It must be light. 3. The driving 

 power must be transmitted elastically. Sponge rubber fulfills 

 all these conditions. Tires filled with this material were driven 

 1.950 miles, with an average speed of 35 miles per hour, without 

 any deterioration of the filler. 



As would be expected, the cellular nature of sponge gives it 

 great insulating properties, both in respect to heat and sound. 

 It is proposed to use the material for the construction of sound- 

 proof rooms, telephone booths, under musical instruments, and 

 under vibrating and hammering machines, etc. It is proposed 

 also for clothing for aeronauts and arctic explorers. 



So far we have spoken only of soft sponge rubber. Hard 

 sponge rubber is also available. It is prepared from soft sponge 

 by further vulcanization. It is understood that the soft sponge 

 is secured by properly regulating the time and temperature of 

 the cure. The stock is made up with sufficient sulphur to effect 

 the transformation to ebonite, so that after producing soft rub- 

 ber further vulcanization takes it over to hard sponge. 



This material has an apparent specific gravity of 0.2 to 0.065, 

 which is yi to 1/6 that of cork, and J4 to 1/12 that of wood. 

 It may be worked in any way customary with hard rubber, 

 such as sawing, boring, machining, etc. It still has the cellular 

 structure of soft sponge, and therefore its insulating properties 

 are not in the least affected. However, it is now not so sus- 

 ceptible to temperature change, and will stand temperatures up 

 to 130 degrees C. It is recommended for iccbo.K walls, covering 

 for flasks, and other insulation problems. 



Hard sponge has considerable strength, and has been proposed 

 as a material for the framework of aeroplanes. It has also been 

 recommended as a material for constructing automobile bodies. 

 [Andrew H. King in "Metallurgical and Chemical Engineering."] 



