Ill 



water, this compound, like that of Lieben, is resolved into hydro- 

 chloric acid and aldehyde. By heat, it is broken tip into aldehyde 

 and the body C 8 H s O 2 C1 2 . The authors propose for it the name 

 protoxychloride of aldehyde. 



2. Aldehyde and Hydriodic Acid. 



By the action of hydriodic acid on aldehyde a compound is pro- 

 duced that decomposes with water into the aldehyde and the acid 

 again, on which account it could not be purified. On heating, it is 

 suddenly decomposed at 70 C., leaving a black resinous residue, 

 which on distillation gave off vapours of iodine. In its mode of 

 formation it is analogous to the bodies produced by the action of 

 hydrochloric acid on aldehyde. 



3. Aldehyde and Sulphurous Acid Elaldehyde. 



Dry sulphurous acid gas led into anhydrous aldehyde in cold water 

 is absorbed with great avidity, 1 1 grammes of aldehyde absorbing 1 9 

 grammes of the acid, whilst an increase of volume takes place. The 

 absorption- coefficient of aldehyde for this acid was found to be T4 

 times greater than that of alcohol for the same, and seven times greater 

 than that of water for it. No chemical combination appears to take 

 place, as, on passing a stream of carbonic acid through the fluid at a 

 slightly elevated temperature, almost all the sulphurous acid can be 

 driven out again. If aldehyde, saturated with sulphurous acid, be 

 left for about a week at ordinary temperatures in a well-stoppered 

 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 witlf 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 4 H 4 O 2 . 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 124C., 

 and solidify ing-point 10 C. Whilst solidifying it likewise starts 



