262 Correspondence of J. Nickles. 
giving a very small flame, nearly like that from brandy. The oil from 
the peat is a viscous blackish nit of strong odor ; it is subjected to 
a new distillation, and resolved wholly into a permanent gas and hydro- 
gen very richly carburetted. This mixture is strongly llaceinanaee 
iving a flame six or eight times brighter than the first and of m 
lively Eiestoe. The two are mixed, and a gas of satel 3 pe 
acter ar renns which is delivered over for consumptio 
ault has made his trials with a yin HS method which 
will soon age made known. Its unit was not a single wax-candle, but a 
collection of seven candles, arranged in a hexa onal manner with 
y this method, a mean of five determinations gave for a burner of 
peat gas a light equivalent to 234 candles; and the same burner with 
coal gas 6,3, candles. 
The illuminating power. of the pure oil from peat—the illuminating 
material ‘ par excellence””—has been found, at equal pressures, 705, 
the intensity for coal gas being 100; and with equal volumes their 
age eee are as 75 LOM: 
number now for the Ja of the opera is 898. There has hence been, 
from 1715 to 1855, a rise of nearly a tone in = diapason of the or- 
chestra. This rise has taken place mainly in the present century, and 
most rapidly in the last 25 years. The following facts will give some 
“idea o the change. 
‘ (1) The Za of the Royal Chapel es 5 ee XVI. corresponded to 
bi vibrations ; (2) in 1808, the Ja of a flute of Holzappe!, as esti- 
ted by Delezenne, was 853; ees diapasons of the same e och 
848 
servatoire ; (4) j in 1834 the i at the Opera gS to 8674 
vibrations, at the en 870; (5) in 1855, finally, i la of the 
operas is 898 vibratio 
Thus since 1823 A i rise has been nearly a semitone ; and it is there- 
fore not astonishing that tenor voices should be so rare. 
his rise in the diapason has not reached its limit. In fact, since 
wind instruments have e had great importance in the orchestra, they have 
necessarily, in consequence of their sonorousness, imposed their tone 
*on stringed instruments. But the diapason of these instruments tends 
the fullest sonorousnese, it is papa to give the strings a ‘tension very 
_near that which is necessary to break them; and consequently, a3! she 
