Single blocks of Stone. 375 
hydrogen loses much of its odour, and the alcohol, when 
water is added to it, becomes milky, and in a close vessel 
it deposites, in the course of a few hours, an odoriferous 
volatile oil, which was contained in the gas, and which 
gave it its Welt known smell. Beraels US... 
9. When Hydrogen gas is substituted for azotic gas in 
the mixture which constitutes atmospheric air, and this 
mixture is respired by men or other animals, it very soon 
throws them into a profound sleep, without appearing to 
a have any injurious: effect, especially if a little common air 
_ is admitted to the mixture ; but if in this composition of 
| air carbonated hydrogen is lvabstitated for azote, the mix- 
ture when respired i is highly deleterious. Idem. 
» Whena few drops of J ce nitric acid are let fall 
into a flack of i drogen, th n becomes 
are 2s or 5 cubic inched, de. 
11. Single blocks of Stone. ‘The enormous columns of 
peite, destined for the portico of the new church now 
uilding in the place d’Isaac at St. enue are very 
remarkable. In order to form a proper estimate of their 
size, we will here state the comparative magnitudes of the 
largest blocks known, both ancient and modern. Ist. The 
column of Alexandria commonly called Pompey’s pillar, 
bay which holds the first rank. It is of a single tock of Red 
°" feet 4 inches 11} lines. — od. T 
of the portico of the Pan ntheon, height 46 feet 9 inches 11 
lines, “5th. Columns of the cathedral of Casan, at St. 
iF =e “it 42 feet. 6th. Two columns of the 
ata 
