232 



THE INDIA RUBBER WORLD 



[April i, 1904. 



30 minutes to 260° F. 



90 minutes at 260° F. 



The second formula, which is more generally used, is for a 

 much slower operation, and is as follows : 



30 minutes from the closing of the vulcanizer until the ther- 

 mometer indicates 130° F. 



30 minutes to 160° F. 



30 minutes to 180° F. 



60 minutes to 200" F. 



60 minutes to 2:5° F. 



60 minutes to 230 F. 



60 minutes to 240° F. 



60 minutes to ■ 248° F. 



60 minutes to 255° F. 



iSminutesto 258° F. or 260" F. 



These are the temperatures of the vulcanizing atmosphere — 

 not of the goods themselves. 



Each of these formulas is used in the curing of rubber boots 

 and shoes, and each produces the same vulcanizing effects. It is 

 sife to say that substantially all the rubber boots and shoes 

 made in the United States are cured according to formulas 

 practically like one of the two given above. As the value of 

 such goods produced in the United States in 1903 was upwards 

 of $45,000,000 the formulas must be very common and well 

 known. 



It is at once apparent even from a casual inspection of the 

 formulas, that each is arranged to produce vulcanization 

 through a combination of temperatures, and also that the two 

 combinations are totally different. In the first the average 

 temperatures are much higher than in the other, and the chief 

 part of the vulcanization must take place while the temperature 

 of the chamber is above 250°. In the second, as the operation 

 ceases as soon as the temperature of 258° or 260 is reached, 

 and as the rate of the union of sulphur and rubber rapidly in- 

 creases with each increase of temperature and as rapidly de- 

 creases with each reduction of temperature, the chief part of 

 the vulcanization must take place below the indicated tempera- 

 ture of 250 . It is probable that the effective temperature 

 would average no higher than 238°, for the same goods are as 

 well vulcanized in 2'A hours at 238° (that being the actual tem- 

 perature of the rubber) as when vulcanized according to either 

 of the two given formulas. 



The fact that the same vulcanizing effects are produced by 

 the use of two totally different formulas, each of which is made 

 up from a combination of many various temperatures, is a con- 

 firmation of the law given above in this article, which has been 

 established by direct experiment. 



It is important that this law should become generally known 

 among manufacturers, as there is always a possibility of im- 

 provement in a product when the laws governing its produc- 

 tion are known. Too little attention has been paid in the past 

 to seeking to discover the laws which govern the vulcanization 

 process. Doubtless enough facts are already known from 

 which several other general laws of vulcanization could be de- 

 duced if proper pains were taken to collate them. Dr. Weber 

 has been almost the first to seek to generalize facts into laws. 

 But notwithstanding his researches, the field is still large 

 enough for a great deal of investigation. In fact when we 

 consider the great number of different varieties and qualities 

 of rubber and the fact that each of them must have its own 

 proper treatment, the field seems so vast that we wonder if it 

 can ever be fully explored. 



The second given formula, in itself, contradicts a notion that 

 prevails to some extent that rubber does not vulcanize below 

 239 — "the melting point of sulphur." If the bulk of the rub- 

 ber boots and shoes in this country are vulcanized at an effec- 

 tive temperature lower than 239 , as would appear to be the 



case, it is difficult to see on what' such a notion could be 

 founded. The fact is that nothing could be further from the 

 truth. It is even probable that the sulphur in a rubber com- 

 pound does not melt below 248° F., the melting point of pris- 

 matic sulphur. But whatever may be the melting point, the 

 fact that the sulphur is melted in the compound has not the 

 slightest effect upon the union of rubber and sulphur. The 

 rate of this union increases with each increase of temperature 

 up to about 310 or 315°. after which the rate decreases, not ac- 

 tually but proportionately. Up to that temperature, the rate 

 of the union increases not in a fixed ratio but in a constantly 

 increasing ratio. When the temperature approaches and passes 

 239 , there can not be observed the slightest indication of any 

 change in the rate of increase of that ratio. So when the tem- 

 perature approaches and passes 248° there is not the slightest 

 indication of any change in the rate of increase of the ratio. 

 This statement has been confirmed by the result of a large num- 

 ber of vulcanizations of the same compound under identical 

 conditions both at 238° and 249 , and at various temperatures 

 both just belowand just above each of those two points. 



Note. — In response to many inquiries as to the authorshipoi this se- 

 ries of articles, we would say that they are from the pen of one of the 

 best known rubber manufacturers in America and are the result of a 

 great variety of experiments that are constantly going on in his works 

 and under his personal supervision. — The Editor. 



PROBST'S LIFE SAVING SUIT. 



T 



HE life saving apparatus invented by M. Joseph Probst, of 

 Geneva, Switzerland, is one by means of which each 

 man becomes his own life saver. That is to say, it is a suit 



which, in case of disaster, 

 the passenger can immedi- 

 ately don, with the assur- 

 ance that, no matter how 

 long he may be buffeted on 

 the surface of the waves, 

 he may exist without diffi- 

 culty until picked up. The 

 inventor has himself fear- 

 lessly demonstrated the 

 utility of his invention by 

 remaining in the water for 

 a month, and by means of 

 the food carried in the suit 

 saving himself from starva- 

 tion. His first experiments 

 were made in the lake of 

 Geneva, when he remained 

 15 days in the water to the 

 astonishment of the people 

 of the lake city. The cos- 

 tume is made of India-rub- 

 ber, opens in the center, 

 and is easily put on, and 

 has nothing in its construc- 

 m. joseph probst, of qeneva, in his tion t0 confuse the wearer 

 life saving suit. when trying to adjust the 



suit in moments of excitement. The legs and feet fit into trous- 

 ers weighted at the ends, and on the outside are airtight 

 pockets large enough to contain lamps, matches, food stores, a 

 trumpet, and an instrument by means of which the attacks of 

 predatory fish may be repelled. The dress is so buoyant that 

 nearly half of the body remains above water and one can lie 

 down or stand up in it. 



