312 Royal Society :— 
bottle, it suffers in this time almost a complete change into a body 
for which the authors propose at present the name Elaldehyde. 
To obtain it pure, the fluid is mixed with as much water as is neces- 
sary to dissolve it up; the acid is saturated by degrees with chalk, 
and the fluid obtained is distilled so long as oily drops pass into the 
receiver. The common aldehyde is separated in a resinous form by 
digesting for some time with solution of caustic soda or potash. By 
repeated distillation, the elaldehyde can be obtained free from every- 
thing but a little water. Analysis gives the formula of this aldehyde 
as C,H,O,. It is therefore isomeric with common aldehyde. As 
it was obtained in quantity by the foregoing method, its properties 
were further examined. Its boiling-point was found to be 124°C., 
and solidifying-point 10°C. Whilst solidifying it likewise starts 
into crystals, the melting-point of which is also 10° C. The alde- 
hyde here described under the name Elaldehyde is identical with 
that of Weidenbush*. Its mode of production from common alde- 
hyde is the same; its boiling-point likewise agrees with that of 
the aldehyde of Weidenbush. 
The elaldehyde of Fehling the authors believe to be identical 
with that they have obtained, and also that obtained by Weidenbush. 
That which goes far to prove the identity of the two latter is their 
vapour-densities. That of Weidenbush’s is given as 4°58, whilst that 
of Fehling’s is 4°52; both are converted into common aldehyde by 
heating gently with dilute sulphuric acid, and both crystallize at low 
temperatures. The only material discrepancy between them is the 
boiling-point of 94°C. given by Fehling for elaldehyde, whilst Wei- 
denbush gives the boiling-point of his aldehyde as 125°C. 
Ill. Oil of Bitter Almonds. 
1. Oil of Bitter Almonds and Hydrochloric Acid. 
This acid does not combine with oil of bitter almonds. Ex- 
periments made in sealed tubes, heated first to 100° C., and after- 
wards to 200°, gave no signs of a combination having been effected. 
2. Oil of Bitter Almonds and Hydriodie Acid. 
Much better results can be obtained when hydriodie acid is 
allowed to act on oil of bitter almonds. The gas is absorbed, pro- 
ducing an increase of volume and of temperature, and at the same 
time a little water. At the end of the operation two layers appear, 
of a dark-brown colour. The upper one, which is about a sixth 
part of the quantity of the under one, consists of concentrated hy- 
driodic acid, whilst the under one, a heavy oil, is a compound of 
iodine and oil of bitter almonds. To obtain the substance in a pure 
state, it was first washed well with water to remove excess of the 
acid; next treated with moderately strong solution of sulphite of 
soda, to remove any excess of oil; lastly, on washing with water, the 
salt was removed from it. It can be dried rapidly over sulphuric 
acid at a temperature not higher than 20°C. A higher temperature 
produces gradual decomposition. In the preparation of this sub- 
stance, 6 grammes of oil of bitter almonds absorbed 11 grammes of 
hydriodic acid gas, Analyses of the substance lead to the formula 
4 * Chem. Gaz, vol. vii. p. 34. 
