Mr. Haidinger on the Specific Gravity of Minerals. 67 



Space occupied by each ounce of Ova cultivated. 



In the first age an area of square Braccia . • 4 



In second an area of ditto . . 8 



In third an area of ditto . . 19 



In fourth an area of ditto . . 45 



In fifth an area of ditto . . 100 



Note. — The Braccio di Milano is divided into 12 ounces 

 or inches, and corresponds to 5,95 palms, which may be cal- 

 culated at 22 English inches nearly. 



Amount in Weight of Mulberry Leaves consumed by the Silk 

 Worms. For every ounce of Ova, there have been consumed 

 1078 lbs. of Leaves, divided as follows, viz. 



First age eaten lbs. 4 



Second do. . 12 



Third do. . 40 



Fourth do. . 120 



Fifth do. . 732 



lbs. 908 



Leaves, &c. left destroyed unused. 

 In first age . lb. 1 



In second do. . 2 



In third do. . 6 



In fourth do. . 18 



In fifth do. 68 



lbs. 95 

 In the course of the management of the silk-worms, the 



1073 lbs. of leaves from the tree (from evaporation, &c.) will 



have lost 70 lbs. 



Note. — There have been devoured by the silk-worm about 



515 lbs. of pure mulberry leaves. The 1073 lbs. of leaves as 



taken from the tree will yield 80 lbs. of coccoons, calculating 



from one ounce of ova. 



Art. IX. — Account of the Specific Gravity qf several Mine- 

 rals. By William Haidingkk, Esq. F.R.S.E. Com- 

 municated by the Author. 



The specific gravity of minerals is one of those physical pro- 

 perties which are most useful for the student who intends to 

 become acquainted with the inorganic productions of nature, 

 since it can be very easily ascertained to a considerable de- 

 gree of accuracy, and is constant in minerals of the same spe- 

 cies, or at least ranges within very narrow limits, if we have 



