CONVERSAZIONE. 
G87 
■porcelain crucible; a ring of glass, such as is used for microscopic mounting, 
is put round it, and a circular disk of thin glass is placed on the top of the 
ring. The heat of a spirit-lamp is then applied to the porcelain, the alkaloid 
fufees, and a deposit is ultimately obtained on the glass, which when examined 
by the microscope is seen to possess a crystalline form, and which, it is stated, 
also answers to the colour tests for strychnia. The sublimate obtained from 
solania is said to be sufficiently characteristic for the recognition of that alka¬ 
loid. Dr. Gladstone kindly lent the apparatus for obtaining the absorp¬ 
tion of spectra of different liquids contained in hollow wedges, and Mr. 
Tribe, showed a number of the spectra during the evening. The physical ex¬ 
amination by this means of different liquids is daily becoming of more import¬ 
ance, not only in research, but also in the identification of substances. Mr. 
Deane contributed a large number of specimens illustrative of the papers on 
Microscopic Analysis applied to Pharmacy, which were read by himself and 
Mr. Brady at the meetings of the Pharmaceutical Conference, and have been 
published in this Journal. Thus the characteristic crystals obtainable from 
tincture of opium, Battley’s solution, extract of meat, etc., were shown under 
a number of microscopes. The instruments used for this purpose were fur¬ 
nished by Mr. How, who has recently brought out a new student’s microscope, 
which is very cheap and, judging from those exhibited, exceedingly good. Mr. 
How also exhibited a new and very convenient apparatus, designed by IMr. 
Keates for determining the igniting-point of petroleum, coal oil, photogen, etc. 
Messrs. Spfencer, Browning, & Co., showed the new micro-spectroscope, designed 
by Mr. Sorby, F.R.S., and Mr. Browning. This instrument can be attached 
to any ordinary microscope. It is inserted in the place of the eye-piece, and 
enables the operator to obtain the spectrum of the light from any object, either 
opaque or transparent. Thus the spectra of very small quantities of blood, 
aniline colours, etc., can be easily observed ; moreover the apparatus affords the 
means of comparing the spectrum from one substance with that of another, 
and it therefore constitutes a valuable means of identifying a number of bodies. 
For instance it greatly facilitates the recognition of blood-stains, often a me¬ 
dical legal question of great nicety. Messrs. Spencer and Browning also exhi¬ 
bited a new form of direct vision spectroscope, and a spectrum telescope for 
examining the spectra of stars and comets. 
Professor Wheatstone, F.R.S., kindly contributed some new instruments of 
his invention. One was a machine for showing the augmentation of the power 
of a magnet by induction currents produced thereby and reacting on the magnet 
itself. Another instrument which excited great interest was a telegraph ther¬ 
mometer. By its means it is possible to read with accuracy the temperature of 
an ocean bed, or any place inaccessible to the observer himself. It consists 
of two boxes connected together by small telegraph wires. The first con¬ 
tains a delicate Breguet metallic thermometer. The second is furnished with 
a Fahr. and Cent, scale, and a needle capable of moving along it. Upon turn¬ 
ing the handle of the second box, a current of electricity passes through the 
wires, and causes the needle to point to the exact temperature which the thermo¬ 
meter in the other box is at that moment recording. Professor Wheatstone also 
sent a compact and elegant magneto-electric machine, generating currents of 
electricity suitable for the exhibition of vacuum tubes, etc. Messrs. Murray 
and Heath contributed a number of microscopes of different kinds, including 
one adapted to sea-side use, also a demonstrating class microscope, and a very 
cheap and excellent instrument for students. They also showed a new telescope 
lamp suitable for use with the microscope, or for similar purposes. It consists 
of three tubes having spiral movements one within the other, the oil or paraffin 
being contained in the inner one. The height of the lamp is regulated with 
the greatest nicety by simply turning one tube within the other; the spiral 
