220 ANNUAL OF SCIENTIFIC DISCOVERY. 



that the sweet principle of frozen potatoes is due to the conver- 

 sion of starch into sugar. After a long series of experiments, he 

 concluded that this sweet principle was caused, during the freez- 

 ing and thawing, by the sap bursting the cell and thus destroying 

 vitality; at the same time decomposition sets in, whieli, though 

 retarded by the cold, is not entirely arrested; the more so as at 

 the season most likely to freeze, and especially during a snow- 

 storm, there abounds that powerful oxidizing agent, ozone. The 

 outer portions, no doubt, are first attacked by it, and may thus be 

 transformed into diastase, a body possessing the power of convert- 

 ing a comparatively large quantity of starch first into dextrine, 

 and then, at the temperature of 140° to 170°, as in the process of 

 cooking, into sugar. 



ON THE FORMATION OF THE DIAMOND. 



Researches on this subject have lately been made by Messrs. 

 Goeppert and D. Brewster. The black diamond of Bahia is, 

 according to Mr. Goeppert, a mixture of amorphous carbon and 

 diamond. M. Liebig's experiments on its combustion also agree 

 with tliis statement. It often happens tliat the diamond incloses 

 other crystals ; iron pyrites, particularly, has been noticed in it 

 by Mr. Hartwig. Sir David Brewster calls attention to the micro- 

 scopic cavities existing in this as well as in other gems, as in the 

 topaz and emerald. These cavities are found to be often very 

 numerous in certain dark diamonds ; they, thus dispersing the rays 

 of the light, are tiierefore of no value in jewelry. Mr. Goeppert 

 remarks that the diamond must originally have possessed a certain 

 plasticity ; we notice, in fact, in a diamond belonging to the Em- 

 peror of Brazil, the impression yet of a sand grain. The black 

 as well as the crystallized white ones bear also the signs of analo- 

 gous impressions produced by foreign bodies. Some investigators 

 believe they have recognized the cellular tissue of plants in the 

 ashes resulting from the combustion of this gem. Mr. Goeppert, 

 however, has not yet detected with certainty any traces of organi- 

 zation, neither in the diamond nor in its amorphous form, the 

 plumbago. As to the question so often discussed, whether the 

 diamond be formed by Plutonic or Neptunic action, the latter 

 naturalist is of the opinion that the first hypothesis is scarcel}'' ad- 

 missible, experiments having shown that the diamond is changed 

 into a kind of coke whenever exposed to the intense heat of a 

 galvanic battery. The second hypothesis, attributing its forma- 

 tion to Neptunic action, is sustained by the authorities of Newton, 

 Brewster, and Liebig, being also that which is best in accordance 

 with all that is known about the gneiss, itacolumite, and the met- 

 amorphic rock in which it is^ found. The character of these rocks, 

 however, does not allow us to attribute to them a Plutonic origin. 

 — Cosmos. • 



The origin of the diamond has been a subject of much specula- 

 tion, as the circumstances under which it is found in nature afibrd 

 no clue to the process of its formation. 



