126 



THE POPULAR SCIENCE MONTHLY. 



due if the heating was prolonged for a suf- 

 ficient time. The remaining solution from 

 ■which this organic substance had been sep- 

 arated gave no reaction with hydrochloric 

 acid, the absence of silver being thereby 

 proved. A stream of sulphureted hydro- 

 gen gave a precipitation in which a very 

 little quantity of sulphuret of mercury was 

 discerned. Very strong reactions of phos- 

 phoric acid and lime were observed in the 

 nitric-acid solution with the ordinary re- 

 agents. This singular tartar is consequent- 

 ly not silver amalgam, but the same material 

 of which teeth are generally made, modi- 

 fied, however, by the influence of a small 

 quantity of mercury. That metallic mer- 

 cury is easily absorbed by the animal econ- 

 omy is well known ; it seems, however, not 

 to have been noticed on the outside of the 

 teeth before. 



The Grave-Digger Beetle— In order to 

 test the strength of the grave-digger beetle 

 {Necrophorus Germanicus) Mr. Gleditch, an 

 entomologist, half filled a glass vessel with 

 earth, into which he put four of the beetles 

 with a dead linnet. The grave-diggers im- 

 mediately began to excavate beneath the 

 dead body of the linnet, shoveling away the 

 earth on each side. After laboring for near- 

 ly two hours, one of the beetles was driven 

 away and not allowed to work again. The 

 others continued their labor, until one by 

 one they ceased, leaving only one beetle at 

 work. Five hours, more hard work was 

 given by the remaining beetle, who at last 

 sank exhausted on the earth and rested 

 from his task, and finally, suddenly rousing 

 himself, stiffened his collar, and by an ex- 

 traordinary effort of strength lifted up the 

 bird and arranged it within the spacious 

 grave. In three days the grave was finished, 

 and the bird safely deposited within its nar- 

 row limits. During a space of fifty days, 

 these busy workers interred the bodies of 

 four frogs, three small birds, two grasshop- 

 pers, and one mole. This singular occupa- 

 tion, which continues from the middle of 

 April until the end of October, proceeds 

 from an instinctive desire for the preserva- 

 tion of their offspring. Eggs deposited by 

 the' parent in the substances which they 

 inter, when hatched, produce larvae, which, 

 feeding on the carrion which surrounds 



them, grow to an inch in length. These in 

 their turn change into yellow chrysahds, 

 and lastly into beetles ; and the latter, when 

 emerged from the earth, begin to dig graves 

 and inter dead animals for the benefit of 

 another generation. 



A New Mineral White. — For many years 

 chemists have been trying to find some min- 

 eral white which might be substituted for 

 the costly and poisonous white-lead. One 

 of the substitutes proposed was zinc-white 

 — oxide of zinc — but the " body " of zinc- 

 white will not bear comparison with that 

 of white-lead. Oxide of antimony, and the 

 silicates of zinc, magnesia, and lime, were 

 successively tried, but none of these sub- 

 stances proved to be an adequate substitute. 

 Mr. T. Griffiths, of Liverpool, has obtained a 

 mineral white the basis of which is sulphide 

 of zinc, and which Dr. Phipson pronounces 

 to be " in every respect superior to carbon- 

 ate of lead itself," i. e., white-lead. It is 

 obtained by precipitating either chloride or 

 sulphate of zinc by means of a soluble sul- 

 phide — sodium, barium, or calcium sulphide 

 — and precautions are taken lest any iron 

 that may be present in small quantity 

 should be precipitated with tlie white sul- 

 phide of zinc. The precipitate, being col- 

 lected and diied, is transferred to a furnace, 

 there calcined for some time at a cherry-red 

 heat, and carefully stirred so as to bring all 

 parts of it successively in contact with the 

 air. It is then raked out while quite hot, 

 into vats of cold water, where it is levigated, 

 and afterward collected and dried. The re- 

 sult is a very fine white pigment ; its cover- 

 ing power when mixed with oil is about 25 

 per cent, higher than that of carbonate of 

 lead. Phipson's analysis of the new prod- 

 uct sliows it to be an oxysuiphate of zinc. 

 This white is not darkened by sulphureted 

 hydrogen, and its manufacture is perfectly 

 innocuous. 



A Snbstitnte for Gntta-Percha.— We 



take from an English journal the following 

 account of a substance called balata, the 

 milky sap of the bully-tree, which grows in 

 the region of the Amazon and the Orinoco : 

 Balata, we are informed, possesses many 

 of the characteristics of India-rubber and 

 gutta-percha ; indeed, it so closely resembles 



