1817.] ' Philosophical Transactions, 1816. 465 
the circulating Blood, more particularly that of the Colchicum 
Autumnale upon Gout. By Sir Everard Home, Bart. 
It is well known that mercury produces the same effects on the 
system, whether it be introduced through the absorbents, or by the 
stomach. The author made an experiment with a dog to ascertain 
whether this was the case likewise with the eau medicinale. He in- 
troduced a certain quantity of this substance into the circulation of 
a dog through the jugular vein. He made the dog afterwards 
swallow a quantity of the same medicine. The effects in both cases 
were the same. 
13. Appendix to the preceding Paper. By Sir Everard Home, 
art. 
In this appendix he gives the account of the effects of the intro- 
duction of a large quantity of eau medicinale into the circulation of 
a dog. It produced all the symptoms induced by swallowing an 
over dose of the medicine, and occasioned death. 
14. On the cutting Diamond. By W. H. Wollaston, M.D. 
Sec. R.S. 
The diamonds chosen for cutting are all crystallized. The sur- 
faces are curved ; and hence the meeting of any two of them pre- 
sents a curvilinear edge. If the diamond be so placed that the line 
of the intended cut is a tangent to this edge near its extremity, and 
if the two surfaces of the diamond laterally adjacent be equally in- 
clined to the surface of the glass, then the conditicns necessary for 
effecting the cut are complied with. A simple fissure is effected 
which need not be more than ;1,th of an inch in depth. Whena 
force is applied at one end of this fissure, a crack extends itself 
almost certainly in the direction of the fissure. Dr. Wollaston 
found that other bodies, as sapphyr, ruby, spinell, when ground 
into the same curve surfaces as the diamond, would also cut glass ; 
but the edges very speedily lost the requisite shape. 
15. An Account of the Discovery of a Mass of native Iron in 
Brasil. By A. F. Mornay, Esq. 
This mass was found in about 10° 20’ S. lat., and about 33’ 15” 
long. W. from Bahia. It had been discovered in 1784, and an un- 
successful attempt made to bring it to Bahia. It is about seven feet 
long, four feet wide, and two feet thick ; but of an irregular shape. 
Mr. Mornay calculates its solid contents at 28 cubic feet, and its 
weight about 14,000 lb. Its upper surface is glossy, and chesnut- 
coloured ; being covered with a thin coat of rust, the under surface 
is scaly. 
16. Observations and Experiments on the Mass of native Iron 
Sound in Brazil. By Dr. Wollaston. 
The specimen exhibited a crystalline texture, and was disposed to 
break in octahedrons, tetrahedrons, or the rhomboids formed by 
their junction, It was magnetic by induction, like common iron, 
It was composed of 
Vor. IX. N° VI. 2.G 
