NEW AROMATIC ALDEHYDE OCCURRING IN EUCALYPTUS OILS. 293 



From the mean of these results, or from either, we may consider 

 the formula for the aldehyde to be C 10 H 14 O, especially as this 

 formula was continued by analysis of the silver salt of the corres- 

 ponding acid. 



C 10 H 14 O requires 80 C, and 9'33 H. per cent. 



Oxidation of the aldehyde with potassium bichromate. — It was 

 found that an alkaline solution of potassium permanganate acted 

 very energetically on the aldehyde, so potsassium bichromate in 

 sulphuric acid was used instead; this substance acted much more 

 slowly. By heating directly over a low flame using an upright 

 condenser, or for some hours on the water-bath, a dark coloured 

 cake eventually formed on the surface of the liquid, on cooling, 

 this became quite brittle. The solid portion was collected,, 

 powdered, boiled in a dilute soda solution when the chromium 

 salt was decomposed. The nitrate was acidified with hydrochloric 

 acid, when a colourless acid was precipitated, this was well washed 

 with water and purified from dilute alcohol from which it was 

 obtained in interlaced crystals which gave the material a soft 

 matted appearance. The purified substance melted sharply at 

 110° C; on allowing the melted acid to cool, it crystallised in stout 

 microscopic prisms which melted again at 110° C. The acid was 

 soluble in boiling water, but little soluble in cold water, very 

 soluble in alcohol and in ether, from which it crystallised well. 

 The acid is saturated, as its aqueous solution did not bleach 

 bromine water. The ammonium salt crystallised well, it formed 

 a silver salt readily, also a light blue copper salt with copper 

 sulphate; barium and calcium chlorides did not give precipitates. 

 Ferric chloride gave no coloration in alcoholic solution. The 

 formula for this acid is C 10 H 14 O 2 the aldehyde group alone being 

 oxidised to carboxyl; this is shown by the determination of the 

 silver salt. 0*1905 gramme of the silver salt gave 0*0755 gramme 

 metallic silver, equal to 39-63 per cent, silver, O 10 H 13 AgO. 2 contains 

 3949 per cent, silver. The molecular weight of the silver salt 

 = 272 giving a molecular value for the acid between 165 and 166. 

 C 10 H 14 O 2 = 166. This is, therefore, the corresponding acid of the 

 aldehyde, or aromadendric acid. 



