NOTES. 



127 



the latter substance in its general proper- 

 ties, that much of it is shipped yearly from 

 Guiana and sold for that article, although 

 in some respects it is greatly superior 

 to gutta-percha. Like gutta-percha and 

 India-rubber, this gum is obtained by mak- 

 ing an incision in the bark of the ti'ee, and 

 allowing the sap to ooze out and either co- 

 agulate in a lump or flow slowly over a clay 

 form so as to produce a " bottle " or any 

 other pattern that may be desired. Balata 

 is tasteless, gives out an agreeable odor 

 on being warmed, is tough and leathery, is 

 remarkably flexible, and far more elastic 

 than gutta-percha. It can be softened and 

 joined piece to piece indefinitely, at a tem- 

 peratijre of about 120° Fahr., but requires a 

 beat of 270^ before it melts. It is com- 

 pletely soluble in benzol and bisulphide of 

 carbon when cold. Turpentine dissolves it 

 with the application of heat, while it is 

 only partially soluble in anhydrous alcohol 

 and ether. It becomes strongly electrified 

 by friction, and is a better isolator of heat 

 and electricity than gutta-percha. Caustic 

 alkalies and concentrated hydrochloric acid 

 do not attack it, but concentrated sulphuric 

 and nitric acids do. A sort of artificial 

 India-rubber, called " kerite," invented by 

 A. G. Day, of this city, has recently been 

 brought to. notice. It is prepared in the 

 following way : About twenty-seven pounds 

 of cotton-seed oil and thirty pounds of coal- 

 tar are mixed together in a boiler, with suf- 

 ficient heat and for a sufficient length of 

 time to cause them to unite thorougldy. 

 The temperature should be about 300° 

 Fahr., and the time is from three to five 

 hours. The mixture is then cooled to 

 ■from 200° to 240° Fahr., and then linseed- 

 oil (twenty-seven pounds) is added. When 

 the latter has been thoroughly mixed with 

 the other ingredients, twelve to sixteen 

 pounds of sulphur is added gradually, the 

 temperature meantime being steadily raised 

 to about 275° or 300° Fahr. The heating 

 is continued till the mass is vulcanized. 

 When the vulcanization is complete, the 

 compound is finished, and it may then be 

 poured into moulds or pans and allowed to 

 cool for use. The inventor has lately made 

 some considerable improvements in his pro- 

 cess of preparing ozokerite, but it would 

 take too much space to detail them here. 



NOTES. 



The American Association will next year 

 hold its meetings at Saratoga, beginning on 

 the last Wednesday of August. Prof. G. F. 

 Barker, of Philadelphia, is the president. 



Died, September 6th, at Brussels, Ernest 

 Quetelet, of the Brussels Koyal Observatory, 

 aged about fifty-three years. Deceased was 

 the son of the late Prof. Adolphe Quetelet, 

 the eminent statistician, who w'as the found- 

 er of the Brussels Observatory, and its di- 

 rector till his death in 1874. 



All the pterosaurian fossils hitherto dis- 

 covered in the United States are from the 

 Cretaceous. But in the American Journal 

 of Science for September, Pi of. 0. C. Marsh 

 describes a fossil specimen from the Upper 

 Jurassic of Wyoming which proves the ex- 

 istence of that class of saurians in the forma- 

 tion just named. The specimen, which is 

 in good preservation, is the distal portion 

 of the right wing metacarpal, and indicates 

 a small pterodactyl, having a spread of wings 

 of four or five feet. 



A VERT ingenious machine, invented by 

 James H. Williams, was exhibited this fall 

 at a Mechanics' Fair in Boston, viz., a 

 machine capable of indii/ating, six to eight- 

 times per minute, the superficial area of sur- 

 faces, however irregular, not exceeding twen- 

 ty-five square feet. The machine can, for 

 instance, compute in less than ten seconds 

 the square contents of a circle without ref- 

 erence to mathematical rules. It is certain 

 to find practical application in many depart- 

 ments of trade. It is specially of use to 

 leather dealers and manufacturers for meas- 

 uring exactly the superficial area of hides 

 and skins. 



GusTAV Wallis, the botanist, died at 

 Cuenca, Bolivia, June 20th, aged forty-eight 

 years. He first visited South America as a 

 botanical collector in 1860, gathering new 

 and useful species of plants, and during the 

 ensuing eight years traversed Brazil, Peru, 

 Ecuador, Bolivia, Colombia, Panama, and 

 Costa Rica. He next visited the Philippine 

 Islands, but in 1871 he again went to South 

 America, never to return. He died in a 

 hospital, in poverty, " worn out in the cause 

 of science," says Kature. He introduced 

 into European horticulture no less than 1 ,000 

 new varieties from across the Atlantic. 



Good petroleum (kerosene), according 

 to Prof. J. Lawrence Smith, should have 

 the following characteristics : 1. The color 

 should be white or light yellow, with a blue 

 reflection ; 2. The odor should be faint 

 and not disagreeable ; 3. The specific grav- 

 ity, at 60° Fahr., ought not to be below 

 0.795 nor above 0.84 ; 4. When mixed with 



