“ 2 ade Boas Saget Tay > hee aed Fs Se ee 
es +e H. Wurtz on the Indigo Test. 49 
~~ Of the Arachnida I can only say—that a few varieties of 
ie are found, and among them there is one whose feet 
_ when extended cover a surface ‘of three inches diameter; and that 
— 4 small scorpion is occasionally seen, though not at all feared. 
—s The Crustacea and Mollusca are numerous and attractive, but 
_--——s it. is little I can as yet report concerning them. Without having 
: done more than induce the natives to collect for = I have on 
Wee 
ae 
paricage es 
e fifteen or twenty species 
“Of the Radiata I only know that our waters are alive with 
them. Twelve or fifteen species of the Holothuria are foun 
though the varieties most valued in China are cotnpaeniitele 
scarce. Biche de mer has several times been cured here by for- 
eigners for the Hongkong market 
| Art? VI.— Contributions to Analytical Chemistry; by HEnry 
Wortz, of New York City. 
On the Detection of Nitric Acid in solution, with Observations on the 
Action of Sesquisalts of Iron upon Indigo and Metallie Gold, and 
on the Neutralization of the Colors of Metallic Solutions. 
(Read, with experimental illustrations, before the Ameri yer ogertyaiire 
vancement of Science at Baltimore, 1858.) 
In the course of an oy bee now in i tread on the 
ve had constant 
mos 2 
1. The protosulphate of iron test, or method of Richemont. 
This is depends the well-known reddish or purplish-brown 
ior Greducad are the combination of the nitric oxyd formed 
by he: Jeoxydation of free nitric acid by pounds of 
, with the excess of the iron compound. H. Rose, in the 
int ‘edition of his Handbuch,* ranks this test above all the 
* I, 659. 
SECOND SERIES, Vor. XXVI, No. 76.—JULY, 1858. 
7 
