300 ANNUAL OF SCIENTIFIC DISCOVERY. 



RYE IN A WILD STATE. 



M. DE CANDOLLE says, in an article in the Bibliofheque Universelle 

 de Geneve, that " both history and botany agree In rendering it prob- 

 able that wheat, barley, rye, and oats came originally from Asia, es- 

 pecially from the western and central regions of that part of the 

 world." He then cites the large number of botanists and travellers 

 who have written upon this subject, but none of them have hitherto 

 brought forward anything entirely conclusive. "But M. C. Koch, 

 a traveller who has traversed Anatolia, Armenia, the Caucasus, and 

 Crimea, now affirms that he has found rye under circumstances where 

 it appears to be really spontaneous and native. On the mountains of 

 Pont, not far from the village of Dshmil, in the country of Hemschin, 

 upon granite, at an elevation of 5,000 or 6,000 feet, he found our com- 

 mon rye alongside the road. It was thin in the ear, and about 1 to 2 

 inches long. No one remembered that it had ever been cultivated in 

 the neighbourhood, and it was not even known as a cereal. The 

 question appears thus to be decided in the way that history and botan- 

 ical geography rendered most likely." 



GUTTA-PERCHA. 



THIS substance, which is rapidly coming into use, is, as all know, 

 the gum or sap of a tree found in the Indian Archipelago. It has re- 

 cently been found to be composed of three distinct substances, a white 

 matter, which is considered the pure gutta-percha, a substance of a 

 dark brown color, and a considerable quantity of sulphur. Various 

 experiments have been made to ascertain its strength when mixed 

 with other matters, and also to determine what pigments will mix with 

 it, without rendering it brittle, or deteriorating its qualities. From 

 these it appears that the only pigments to be entirely relied on are 

 orange red, rose pink, red lead, vermilion, Dutch pink, yellow ochre, 

 and orange chrome. Under the influence of heat and pressure, gutta- 

 percha will spread to a certain extent, which is greater when it is mixed 

 with foreign matters. All the mixtures of gutta-percha and other 

 substances, except that containing plumbago, are found to increase its 

 power of conducting heat, but in its pure state it is an excellent non- 

 conductor of electricity. The best composition for increasing the 

 pliability of gutta-percha is that formed with caoutchouc tar, and the 

 next best is that with its own tar. The best material known for 

 moulding and embodying is obtained by mingling gutta-percha with 

 its own tar and lampblack. In the process of manufacture, the rude 

 blocks of gutta-percha are first cut into slices, by means of a machine 

 formed of a circular iron plate of five feet diameter, in which there are 

 three radial slots, furnished with as many knives. The slices are 

 then placed in a wooden tank containing hot water, in which they are 

 left to soak till they become plastic. They are next passed through a 

 mincing-cylinder, similar to that used in paper-mills for the conversion 

 of rags into pulp, and then they are thoroughly cleansed in cold water 

 tanks, the water, where the gutta-percha is impure, being mixed with 



