288 
Scientific Notes. 
[April, 
experimenting with hydrogen — in the presence of MM. Berthelot, H. Sainte- 
Claire Deville, and Mascart — M. Cailletet succeeded in observing indications 
of its liquefadtion under conditions of proof which left no doubt in the minds 
of the scientific men who witnessed the experiment. It was repeated a great 
numoer of times. Operating with pure hydrogen compressed to about 
280 atmospheres, and then suddenly allowed to expand, they saw form an 
extremely attenuated and subtle mist suspended in the gas and disappearing 
suddenly. Having liquefied nitrogen and oxygen, the liquefadtion of air is 
thereby demonstrated. It appeared, however, of interest to make this the 
subjedt of an adtual experiment, and, as might be expedted, it succeeded per- 
fectly. I need not say that the air was previously dried and freed from 
carbonic acid. The accuracy of the views expressed by the founder of 
modern chemistry, Lavoisier, is thus confirmed as to the possibility of causing 
air to assume the liquid state, and of producing matter gifted with new and 
unknown properties. 
At a recent meeting of the Academie des Sciences M. Lecoq de Bois- 
baudran exhibited a bar, a sheet, and several crystals of the new metal, 
Gallium , which is harder than iron, yet melts at under the heat of the finger, 
its freezing-point being at about 30°. It is proposed to use it for a thermo- 
meter going up to red-heat. 5000 kilogrms. of ore had to be worked down to 
get 60 grms. of metal. It will now be possible to investigate its physical 
properties. It adheres to glass, and is very brittle ; the colour is nearly that 
of steel ; and the crystals are odahedra. M. Lecoq de Boisbaudran has 
since determined the atomic weight of gallium ; it is ficpg. 
A photo-lithographic plat of the primary triangulation carried on during tho 
summer of 1877, by Mr. A. D. Wilson, Chief Topographer, has just been 
published by the U.S. Geological Survey, under the charge of Dr. F. V. 
Hayden. The area covered by these triangles extends from Fort Steele, in 
Wyoming, Zy., westward to Ogden, in Utah, Zy., a distance of about 
260 miles, and north as far as the Grand Teton, near the Yellowstone National 
Park, including Fremont’s Peak, of the Wind River Range of the Rocky 
Mountains. The area embraces about 28,000 square miles, and within it 
twenty-six primary stations were occupied and their positions accurately 
computed. Besides these occupied stations a large number of mountain peaks 
were located, which in the future will be occupied as points for the extension 
of the topographical work of the Survey. A base line was carefully measured 
near Rawlins’ Springs, on the line of the Union Pacific R.R., and from this 
initial base the work was extended north and west to the valley of Bear River, 
in Idaho, Zy. Here a check base was measured, and the system expanded to 
the neighbouring mountain peaks, to connect with the triangulation, as brought 
forward from the first-mentioned base. Along the line of the Union Pacific 
R.R. the work was connected at six points with the Triangulation System of 
Clarence King’s 40th Parallel Survey. In addition to the importance of this 
sheet as the base of the season’s topographical work, it presents a most 
striking feature in the number of remarkably long sights which were taken 
from some of the most lofty mountains in the area explored. Many of these 
sights were over 100 miles in length, while some reach a distance of 135 miles. 
From Wind River Peak all the prominent points in the Big Horn Mountain 
were sighted ; also the loftier peaks of the Uinta Mountains: the former are 
located 165 miles to the north-east, while the Uinta Mountains are situated 
about the same distance to the south-west. As these ranges were not in the 
scope of the season’s work they are not given on the chart. 
