412 PHYSIOLOGICAL REMAINS. 



in three sovereigns the difference in the water is but 

 twenty-four grains. 



The same sovereign overweigheth an equal weight 

 of lead, four grains in the water, in brass grains for 

 gold : in three sovereigns about eleven grains. 



The same sovereign overweigheth an equal weight 

 of stones in the air, at least sixty-five grains in the 

 water : the grains being for the weight of gold in brass 

 metal. 



A glass filled with water weighing, in Troy weights, 

 thirteen ounces and five drams, the glass and the water 

 together, weigheth severally, viz. the water nine ounces 

 and a half, and the glass four ounces and a dram. 



A bladder weighing two ounces seven drams and a 

 half, a pebble laid upon the top of the bladder makes 

 three ounces six drams and a half, the stone weigheth 

 seven drams. 



The bladder (as above) blown, and the same fallen, 

 weigheth equal. 



it ought to do, come next. See Porta's Natural Magic, 18. chap. 8., and 

 Cusa de Stnticis Experimentis, appended to the edition of Vitruvius pub- 

 lished at Strasbourg, 1550. (The tract is not paged.) 



One of the first determinations of specific gravity results from Vitruvius's 

 statement with respect to Mercury. He says " quum sint quatuor sextario- 

 rum mensuras cum expenduntur invenientur esse pondo centum." Now 

 the congius held, as we know, ten Roman pounds of water, and therefore 

 the sextnrius held five-thirds of a pound ; four sextarii consequentlv of 

 water would weigh six pounds and two-thirds; and comparing this with 

 Vitruvius's statement, the specific gravity of quicksilver is fifteen, a re- 

 sult sufficiently near the truth, but erring in excess. 



It is worth remarking that Vitruvius in the passage I refer to gives the 

 name of minium to cinnabar, not as commonly to red-lead. The name of 

 rermillion must originally have belonged, as the etymology indicates, to 

 kermes or cochineal. There is however a great deal of confusion in these 

 names ; and it would seem from Arrian that the name cinnabar was origi- 

 nally given to cochineal. There is a wonderful story of its being produced 

 by a mixture of the blood of dragons and of elephants. See Vitruvius, 

 book vii. chap. 8. R. L. E. 



