m 



THE INDIA RUBBER WORLD 



[June 1, 191; 



Rubber vnd Eg ' ■ vien. An emulsion is made by mixing 

 three parts of fresh egg albumen with one part of a solution of 

 crude rubber in benzine. This mixture should stand till thor- 

 oughly dried before further compounding on rolls with sulphur 

 and other compounding ingredients for hot vulcanization. 



Vulcanizing Natural ok Akihum Rubber. An English 

 patent (No. 4,263, 1 *> 1 3 ) has been granted for a process 

 of vulcanizing natural or artificial rubber. It consists 

 oi acceleration I>\ 'he addition of small amounts of p nitrosodi- 

 methylanaline or it-, homologues \ mixture of 1(X) parts rubber, 

 1(1 parts sulphur anil one-half pan of the above accelerator can 

 be vulcanized in twenty minutes at 285 degree- Fahrenheit, as 



against one hour without the accelerator. 



i,\ VTIONS \M> COMPARATIVE TESTS ON THE LATEX 



hi Will) \\U l'l \.\T.\T1(>N HEVEA. 



The work of F. Ripean in this connection confirms the view- 

 that the high quality of Brazilian hard cure Para is due to 

 coagulation by the carbon dioxide present in the smoke em- 

 ployed. The author found that in coagulating Hevea latex by 

 means of carbon dioxide obtained by burning charcoal a product 

 was obtained equal to plantation smoked sheets, and it was also 

 Erom tin impurities which impart to the latter its dark 

 color. The pmi.es-, which is said to have many advantages, is 

 M.i easy to carry out in practice. Precautions mentioned in- 

 clude not allowing coagulation to occur naturally nor hastening 

 by heating, or by addition of acids. The coagulum must not 

 be subjected to mechanical working. Good results were ob- 

 tained by the addition of creosote to the latex. 



In the "Journal .if the Society of Chemical Industry." April 

 15. 1915, pp. 34-37, W. A. Caspari writes of his researches in 

 the behavior of colloids inwards pure and mixed liquids. His 

 re-ults show indications, from experiment, that discontinuity 

 between caoutchouc-benzene solution and caoutchouc-benzene 

 gel exists in the neighborhood of one volume of caoutchouc and 

 six volumes of benzene. 



It is significant that the caoutchouc employed absorbed about 

 -ix volumes of benzene before passing into solution. 



MEASURING THE IMPERMEABILITY OF PROOFED CLOTH. 



Cloth waterproofed by rubber proofing, impregnated with 

 alum or other salts, is not completely impermeable to water. 

 \n instrument for determining the degree of impermeability has 

 been devised. As described in a recent communication to the 

 i . of Dyers and Colorists of England, it consists of a cop- 

 per cylindrical box, to which are attached a glass measuring 

 tube and a rubber bulb < In the top of the box are fixed ( by 

 mean- of two screws) two ring-, one of copper and the other 

 of rubber. 



\t the beginning of the experiment the box and the bulb are 

 filled with water, ami on the top of the box is fixed a piece of 

 the cloth to be tested. By pressing the bulb the height of water 

 in the glass tube i, increased, and when the pressure is sufficient 

 10 cm.) small drop- are observed to form mi the surface of 

 the cloth The height of the water column measures the im- 

 permeability i if the cloth 



THE SI30CCO— STURTEVANT INFRINGEMENT SUIT. 



Seven year- ago the Sirocco Engineering Co., which was 

 afterward- absorbed b\ tin- American Blower Co.. brought 

 suit against She If F. Sturtevant Co., claiming infringement of 

 the Sirocco patents. Verdict was given to the \merican Blower 

 ver court and was appealed. Last December the 

 Supremi I ourt oi appeals of the second circuit, which i- the 

 highest court in the land that can pas- upon patent litigation, re- 

 turned a verdict in favor of the I'.. F. Sturtevant Co., reversing 

 the decision of tin- lower court. The court not only stated that 

 the Sturtevant multivane fan was not an infringement nf the 

 ajround that the Sirocco fan patents 

 were not valid. 



TEST FOR FINENESS OF PIGMENTS. 



TNIFORM texture and dependable physical properties in 



^ high-grade rubber g Is are influenced to an important 



extent, although not entirely controlled, by the degree of fineness 

 of the mineral compounding ingredients employed in the mixing. 

 The rubber manufacturer is also interested in the fineness of his 

 pigments as a measure of economy, because the minuteness of 

 the particles of a pigment is an important factor in extending 

 its coloring power. To the paint manufacturer the problem of 

 fineness nf grinding is possibly of even greater importance, be- 

 cause it affects not only the efficiency of his own grinding ma- 

 chinery but the working qualities and color value of his product. 



In the rubber, as in the paint trade, material is customarily 

 purchased on an envelope sample representing the goods, and, 

 speaking only of the rubber trade, the goods are commonly used 

 without any further ado; except, of course, that in the case of 

 special high-grade or otherwise important mixings, resort is had 

 to sifting the dry ingredients through a fairly fine mesh to facil- 

 itate mixing and to insure removal of accidental impurities. 



This is to be commended as a precautionary measure. It 

 should he preceded by a careful standardized test for the ac- 

 ceptance of the various ingredients. In a recent issue of the 

 "( )il, Paint and Drug Reporter" C. D. Holley and J. C. Brier 

 have published their method of test for fineness of dry pigments. 

 with tables showing the results obtained on a variety of mate- 

 rials, most of which are found among rubber makers' supplies. 



The authors state that deciding upon a suitable degree of fine- 

 ness of particles and maintaining an accepted standard in this 

 respect leads to continued controversy between the manufac- 

 turer and the sources of his supply. This is due largely to the 

 fact that the envelope samples, on which goods are purchased, 

 do not fairly represent the deliveries. The necessity thus arises 

 fot a standard basis of fineness that can be designated numeric- 

 ally, and a standard screen has been employed for such measure- 

 ment, having 350 meshes per inch, or 122,500 apertures per 

 square inch. Such a screen is extremely efficient in separating 

 particles of material expensive to grind. It has been demon- 

 strated that particles which will pass through a 350 mesh un- 

 dergo but little actual grinding in the paint mill, whereas the 

 particles retained on such a screen, even though the percentage 

 is comparatively -mall, dull the mills very rapidly and much re- 

 duce their output. 



\\ .aving the material for the standard screen is difficult and 

 expensive because of the precautions necessary to be observed 

 i i -ccure a uniform 350 mesli each way. Its manufacture has 

 been sui i .--ndly accomplished by the Multi-Metal Separating 

 Screen Co., of New York. The wire used in its construction is 

 vanadium bronze, one one-thousandth of an inch in diameter. 

 The spacing of the warp is regulated by a reed consisting of 

 350 teeth per inch and uniformly spaced. The reed measures 36 

 inches long and contains 12,600 teeth. During the weaving the 

 warp wires are kept stretched to the limit of their enduranci to 

 prevent shifting during the process of manufacture. The cr — 

 wires are placed at equal distances from each other in the weave. 

 and the operator of the loom checks this spacing under a magni- 

 fying l;Uis- every eighth of an inch. The resulting fabric has 

 been found sufficiently accurate for the intended purpose. 



The method of testing a pigment with such a screen is simple 

 and expedition-. \ so-called master screen is kept as a stand- 

 ard, and whenever a new one is secured a practical test of the 

 ai i uracy of the new screen is made by using both screens with a 

 pigment that has a considerable percentage of coarse particles. 



A gram -ample nf the pigment under examination is washed 

 through the screen under the water tap, using a soft 1-inch brush 

 to break up the lumps, brushing continually until only the coarse 

 particles remain on the screen, which is then wiped dry on the 

 under side in order to remove as much moisture as possible, then 

 dried on a steam oven or hot plate. The dried residue remain- 



