938 REPORT —1885. 
In the case of thermometers the enamel is caused almost to surround the stem,. 
leaving but an aperture through which to view the mercurial column. This 
enables the graduation to be made and the figures to be etched immediately in 
front of the enamel, and consequently gives them a clearness and distinctness as far 
superior to the ordinary tube as that is to the old-fashioned instrument with clear 
glass stem. 
The application of the enamel to the construction of the variety of fluid 
measuring glasses now in use is quite new, I believe, and will be of great service 
in laboratories and all places where such articles are in use. In this case the 
enamel is not caused to almost surround the measure, but alternate segments of the 
sides of the glass are clear and opaque, so that a view of the fluid being measured 
is obtained through the spaces, and the graduations stand out distinctly on the 
white surfaces. Specimens of the different instruments were laid on the table. 
8. Ow Methods of preventing Change of Zero of Thermometers by Age. 
By G. M. Wutrett, B.Sc., F.R.A.S. 
The author, haying referred to methods which have been adopted at various 
times to rectify the rising of the zeros of mercurial thermometers by age, exhibited 
to the meeting certain instruments which had been annealed in accordance with a 
practice in use for many years in the construction of standard thermometers at 
the Kew Observatory. These have been made by Mr. Hicks, of Hatton Garden, 
who has erected special apparatus for the purpose, and apparently show that 
the desired result has been attained. 
9. On a new and simple form of Calorimeter. 
By Professor W. F. Barrett. 
With this instrument no corrections for the heat capacity of the vessel used or 
of the thermometer are necessary, and only a small correction for the loss by cool- 
ing. The bulb of the thermometer forms the cup that holds the liquid, and the: 
stem the beam of the balance that enables its weight to be found. The tempera- 
ture, T, of the warm liquid is given by the thermometer that plugs the burette as 
the liquid flows into the empty cup, the temperature of which is raised from ¢ to 6. 
If C be the constant of the instrument and W the weight of water used, the heat 
lost is equal to the heat gained by the instrument, or W (T — 6) = C(6 —12), 
whence 
,T-@ 
mith Sere . 
Hence a liquid of sp. heat S and weight W, having an initial temperature T, 
and which raises the temperature of the calorimeter from ¢’ to 6’ is found as 
follows : 
a ke =?) 
hae (T; ip 0’) 
The constant C for each instrument is determined once for all and the opera-- 
tion then becomes a very simple and speedy one. A polished metal cap fits over 
the cup to prevent evaporation. The instrument is the joint invention of the 
es and of Mr. J. McCowan, Demonstrator of Physics in the Royal College of 
cience. 
10. On a modification of the Daniell Battery, using Iron as Electropositive 
Element. By J. J. CoLEMan. 
