Intelligence and Miscellaneous Articles. 591 
HYDRAULIC LIME, 
M. Vicat communicated a paper to the Royal Academy of Sciences 
at Paris on the sole efficacy of magnesia in rendering certain lime- 
stones hydraulic. This paper has for its object the correction of 
an opinion given by M. Berthier in the Journal des Mines of 1822, 
that magnesia alone has no more efficacy than alumina to render 
lime hydraulic; from which it would follow that silex was the only 
essential principle in all cases. 
M. Vicat was for a long time of the same opinion, which he now 
declares is incorrect ; and says that magnesia alone, when in suffi- 
cient quantity, will render pure lime hydraulic. He does not ex- 
plain the degree of energy of these new species of lime, but only 
affirms that they will solidify from the 6th to the 8th day, and con- 
tinue to harden in the same manner as ordinary hydraulic lime. 
Until his experiments are further advanced, he states that the 
proportions of magnesia taken and weighed after calcination should 
be from 30 to 40 of every 40 of pure anhydrous lime. The native 
limestones examined and cited by M. Berthier contained only from 
20 to 26 of magnesia for every 78 to 60 of lime : it is probable that 
this want of proper proportions was the cause of his negative re- 
sults. M. Vicat, in conclusion, points out the importance of these 
observations,—hydraulic lime never having been found in the cal- 
careous formation below the lias is because the dolomites have never 
been examined, but it is now probable it may be found in this 
lower formation.— L’ Institut, No. 153. 
NOTE RESPECTING CERTAIN CONTROVERSIAL COMMUNICATIONS 
LATELY SENT FOR INSERTION IN THIS JOURNAL. 
LIEUT. LECOUNT. 
We have received a letter from Licut. Lecount, claiming the in- 
sertion, in its entire form, of his previous letter in reply to Mr, P. 
Barlow, from which we gave an extract in our last N umber, p. 439. 
Lieut. Lecount makes this claim on the ground “that it is the ge- 
neral practice to allow any person who is attacked in a periodical 
publication the right of replying.” We have merely to observe, in 
answer, that our extract includes the real matter of Lieut. Lecount’s 
reply, and that we omitted only irrelevant matter of a personal na- 
ture, at the same time referring our readers to the pamphlet which 
he has published. We must therefore decline all further allusion 
to the subject. 
We may remark in reference to this, as well as to other cases of a 
similar kind which have lately occurred, that we cannot permit a 
scientific discussion to degenerate into a personal controversy, 
MR. HENWOOD. 
We take the present opportunity of noticing Mr, Henwood’s letter 
in the Records of General Science for May, to which the remark just 
