384 



THE INDIA RUBBER WORLD 



[August i, 1909. 



number of the manufacturing plants have installed apparatus for 

 the extraction of resins and the recovery of the solvents used, 

 and have been successful in treating not only the gum named, but 

 a great variety of medium and lower grade rubbers that carry 

 large percentages of resin. 



Although not a large business in the aggregate, it might be 

 well to mention what the American manufacturers have done in 

 the line ginerally known as dipped goods. By means of automatic 

 machinery, new solvents and special compounding, together 

 with a careful study and adaptation of the Parkes cold curing 

 process, dipped goods, acid cured, have become a staple product. 



The last ten years have seen a very notable change in the atti- 

 tude of American rubber manufacturers toward the so-called 

 rubber chemist. Where he was scoffed at or barely tolerated 

 by the practical man a decade ago, he is to-day a valued and 

 respected member of the general staff. All of the great factories 

 have well-equipped laboratories with educated chemists in charge. 



Of new developments in rubber manufacture there is no 

 other that compares with the manufacture of automobile tires. 

 It is really a new industry, increasing greatly from year to year. 

 This year's estimate of $20,000,000 is likely to be increased by 

 one-half for another year. Indeed, it is probably in a short time 

 the leading line of rubber manufacturer will be pneumatic tires. 



In spite of the fact that American newspapers regularly dis- 

 cover "synthetic" rubber with never-failing enthusiasm, and in- 

 vestors buy synthetic rubber stocks, this grade of gum has not 

 yet assumed statistical importance. 



RUBBER SUBSTITUTES AND PLASTICS. 



/^F all substances in the three kingdoms of nature there has 

 ^^ been found nothing which has the physical properties of 

 india-rubber to an extent which will allow of its substitution for 

 it in making a high quality of goods, but owing to its high price 

 nearly every substance found in nature or manufactured has 

 been tried alone cv mixed with rubber in greater or less propor- 

 tion. The substance which has been found to most closely re- 

 semble rubber in an artificial product is composed of an oil of 

 vegetable or animal nature which contains an .unsaturated fatty 

 acid. These oils have what are known as drying properties ; 

 that is, they absorb oxygen from the air and become hard. This 

 property makes them valuable for use in paints, and the best 

 paint oils make the best rubber substitutes. In making the best- 

 known substitutes the oil is sometimes previously "blown ;" that 

 is, it is highly heated and air is then blown through it. This 

 has a tendency to stiflfen it and make it more "drying" and ren- 

 ders it possible to use less sulphur or sulphur chloride to make 

 the substitute, but it is not usually considered that as good a 

 substitute can be made that way. If the white substitute is to 

 be made sulphur chloride is used, but if dark substitute is re- 

 quired, then free sulphur is mi.xed, and the oil is highly heated 

 till it hardens up to the proper consistency, or rather will harden 

 on cooling. This product is probably the nearest substitute to 

 india-rubber that can be made. 



It has been made from all the drying oils, and particularly from 

 corn oil, which is not a first-class drying oil, and from cotton- 

 seed oil and from oleic acid, which does not dry at all, but prob- 

 ably the value of oils for making substitutes bears direct relation 

 to their value for paints. Of these oils linseed is usually con- 

 sidered the best, but the Chinese wood oil or "tung" oil has 

 greater drying properties, and further has the remarkable 

 property of hardening to a jelly when heated to 400° F. This 

 jelly is insoluble in all ordinary solvents. This property does not 

 seem to have been taken advantage of as yet. 



In addition to the large number of bodies made in a general 

 way as above, and having their value from the properties of a 

 sulphonated oil, a large number of so-called substitutes have been 

 used, although they are hardly more than fillers or adulterants. 



Of considerable importance are the plastics. These are of 



several varieties, of which pyroxylin is important. If cotton or 

 other form- of cellulose be treated with nitric acid and a dehy- 

 drating agent like sulphuric acid, and the treatment is continued 

 for different lengths of time, and with different proportions of 

 chemicals and the other conditions of manufacture are varied, a 

 number of varied products will be formed where the products 

 which are the least nitrated are more soluble than others result- 

 ing from longer treatment. The strongest treatment produces 

 guncotton, but a w-eaker treatment produces pyroxylin, which is 

 soluble, and when mixed with solvents and camphor, the camphor 

 is absorbed, forming the common product known as celluloid, 

 which is one of the most useful plastics. It is not stretchable, 

 however, although in the scientific sense it is elastic. That is, if 

 bent it returns to its original form. This product forms the basis 

 of another class of substitutes and is mixed with rubber in all 

 proportions. 



Cellulose products form another class of plastics. Cellulose, 

 which is the basis of most vegetable fiber, can be made into the 

 colloidal form by several processes and by forming several chem- 

 ical compounds with it. Of course, the pyroxylin previously men- 

 tioned is a cellulose product, but another plastic or a colloidal 

 form of cellulose is known as viscose, or rather its water solu- 

 tion is so known. If a strong alkali is boiled with cellulose and 

 then carbon bisulphide is added, a solution with water is formed. 

 This watery solution is known as viscose and on drying the 

 cellulose is in colloidal form. Viscose has been the subject of 

 much chemical and other experimental work, and large amounts 

 of capital have been invested in the manufacture of fibers from it 

 to produce artificial silk, but it has not yet largely come into use. 

 It is, however, a plastic with a promising future. 



Another class of substitutes have glue as a basis. Glue or 

 gelatine has the property of being hardened and rendered water- 

 proof by chromic acid or acid chromates or bichromates. This 

 substance or the mixtures which produce this substance form 

 another extensive class of substitutes which are the basis of many 

 patents. Formaldehyde has the same properties of hardening 

 glue and this produces a somewhat similar plastic. 



Another plastic consists of casein or that part of milk which 

 forms cheese. Casein has the bad feature that there is no way to 

 free it entirely from water in the process of manufacture, and 

 when this finally dries out after long use the product develops 

 cracks and becomes brittle. 



Of the tars, asphalts, pitches and mineral waxes there is a 

 large number which have been proposed in all forms and in all 

 quantities, but these should be regarded more as compounding 

 agents than as. -substitutes. Of the other classes it is not worth 

 while to classify them as substitutes, but they are either com- 

 pounding ingredients, which are useful as imparting to rubber 

 properties it does not possess of itself, or they are pure 

 adulterants. h. 0. chute. 



New York, July 9, 1909. 



WILL RUBBER GO TO $2.70? 



AHAXDY little book of "Parity Tables" of crude rubber 

 prices brought out by a friend in the trade a few years ago 

 proved of great convenience in The India Rubber World offices 

 - — as for instance in comparing quotations in shillings per pound 

 with francs per kilogram. The book proved less helpful, how- 

 ever, when the price of fine Para went above the limit for which 

 its computations had been made — i. e., 5 shillings 6 pence 

 [= $1.33.8] per pound. Then a similar book, from another 

 source, was helpful for a while longer, having been computed for 

 prices up to 6 shillings [=$1.46]. But even this has become a 

 "back number," and we welcome a comparative sheet got out 

 by the Gummi-Zcititng, in which the figures run up to 25 marks 

 per kilogram [=$2.70 per pound]. It is, of course, not intimated 

 by the compiler that this limit will be reached, but there are 

 persons in the trade who would not be surprised if it were. 



