232 Scientific Intelligence. {Seprr. 
hornets, which I have not yet had time to complete, except with 
respect to hornets. Their cells 1 have every reason to suppose are 
composed of a single layer or division only ; for as they are made of 
large pieces (about the size of a pin’s head) of rotten wood, the 
same pieces may be seen on both sides of the cell; which refutes 
Dr. Barclay’s ideas of their being composed of two layers stuck 
together by an animal glue. 
. ere - 
The different graduation of thermometers in various countries is 
certainly an inconvenience; but, like the different weights and 
measures, it is-an inconvenience hardly capable of being remedied. 
Fahrenheit was the first person who employed mercury in thermo- 
meters, and who made them accurately corresponding with each 
other. His two fixed points were, the temperature of boiling water, 
and the temperature produced by mixing together snow and sal- 
ammoniac. He conceived the mercury to be divided into 11,124 
parts when surrounded with snow and sal-ammoniac. When put 
into boiling water, he found that it expanded so much as to be equal 
to 11,124 + 212 parts. On that account he divided the interval 
between the two points into 2)2 parts or degrees. He marked the 
lowest 0, and the other 212; so that the degrees of Fahrenheit 
denote not only the temperature, but the expansion, of mercury 
from his zero to the point indicated. Thus 32° is the freezing point 
of water, and —33,-> is the expansion which the mercury undergoes. 
when heated from 0 to 32°. This indication of the expansion is an 
advantage which no other thermometrical scale possesses; and ought, 
I think, to induce us to pause before we resolve to Jay it aside. The 
decimal scale wants this advantage, though it possesses some others 
of considerable importance.. De Luc informs us, in his Recherches 
sur les Modifications de Atmosphere (t. i. p. 343), that what is at 
present called the centigrade thermometer was in common use in 
London when he wrote. His book was published in 1772. If this 
was the case, it would be curious to know what induced the British 
philosophers to abandon it. I cannot find that any such thermometer 
is employed by the writers in the Philosophical Transactions. 
The only possible means of changing our thermometer would be 
to persuade the makers to alter the graduation. If both the cen- 
tigrade and Fahrenheit divisions were matked on the scale, J think 
it would be an improvement. 
IV. Chemical Nomenclature. 
(To Dr, Thomson.) 
SIR, | 
As a philosophical journalist, you are in some degree invested with 
the character.of arbiter of technical nomenclature; and as chemists 
are indebted to you for the introduction of the useful terms pro/- 
oxide, &c. you may do some good by protesting against the intro- 
duction of similar terms leading to confusion instead of perspicuity. 
I mean prosulphate, prochloride, &c. Surely writers need not be 
se es 
