1817.] during the Year 1816. 89 
seized with violent pains, &c. owing to a concreted mass of the 
magnesia having accumulated in some portion of the larger intes- 
tines. She was restored to health in consequence of the removal 
of the obstruction by means of cathartic medicines. 
XI. ZOOLOGY.* 
The only important improvement in this branch of natural science 
is a new distribution of the animal kingdom by Dr. H. de Blainville, 
published in the Bulletin des Sciences for this year; but as it is our 
intention shortly to give an analysis of this ingenious system, we 
shall only observe that animals are divided by this learned anatomist 
into 25 classes. 
In this place we shall correct an erroneous statement published in 
our translation of Cuvier’s account of the proceedings of the Insti- 
tute of France, viz. that homoda is the only genus of sodophthalmous 
crustacea having the peduncle of the eyes composed of two joints, 
this structure variously modified being common to all the animals of 
that group. (Bull. des Sciences, 1816, p. 14.) 
Risso’s long expected work on the Crustacea of Nice is published 
in Paris, but has not yet reached this country. 
ARTICLE II. 
Further Observations respecting the Decomposition of the Earrus, 
and other Experiments made by burning a highly compressed 
Mixture of the Gaseous Constituents of Warrr. Ina Letter to 
the Editor from Edward Daniel Clarke, LL.D. Professor of 
Mineralogy in the University of Cambridge, and Member of the 
Royal Academy of Sciences at Berlin, &c. ; being a Continuation 
of the Article published in a former Number of this Work. 
(To Dr. Thomson, ) 
SIR, 
In my last letter to you I mentioned an explosion; in conse- 
quence of which, my apparatus being destroyed, a temporary sus- 
pension of my experiments necessarily took place. ‘The cause of 
that explosion may be now explained. Upon a careful examination 
of the fragments of the glass tube I then employed, and by com- 
paring them with another which J had used before during nearly a 
quarter of a year, until it was reduced to a piece not exceeding 14 of 
an inch in length, it appeared that I had substituted a tube of -. of an 
. - 60 
inch in diameter for a tube whose diameter only equalled .2. of an 
0 
inch. The difference, indeed, is hardly perceptible tothe eye, and 
may be considered as of little importance; but it is nearly that of 
two to one; for the areas of the sections of cylindrical tubes being 
s the squares of their diameters, the area of a tube whose diameter 
equals ;!, of an inch is to the area of a tube with a diameter of cate 
as16to9, Yet it is extremely desirable that experiments should 
be made with tubes whose diameters are, at the least, equal to ais Of 
an inch; because the heat is thereby rendered incomparably 
greater ; butas the danger is also greater, it is necessary to devise 
* For this article Lam indebted to a friend, 
