1 1 u • aldehj de < rj ptal had, up to quite recently, escaped us, because it does 

 no1 form a solid compound with sodium bisulphite, and also because the liquid 

 combination is not decomposed by sodium carbonate, so that in previous 

 investigations it had been thrown away. As this aldehyde had eluded us lor 

 twenty y/ears, it was decided to name it cryptal. Now that it has been found 

 it is perhaps remarkable that it can be separated and isolated more satisfactorily 

 than either cuminal or aromadendral, and consequently can be prepared in a 

 state of purit} . 



Cuminal readily forms a solid compound when shaken with a 30 per cent, 

 solution of sodium bisulphite, and aromadendral mostly combines in the solid 

 form also, but cryptal only forms the liquid combination. The bisulphite com- 

 pound with both cuminal and aromadendral is decomposed bv sodium carbonate, 

 but that with cryptal is not so changed, and a solution of sodium hydrate is required 

 to set the aldehyde free. A further means of purification is that cryptal combines 

 quantitatively with a 35 per cent, solution of neutral sodium sulphite in the cold, 

 and in this way can be separated from the other aldehyde, which also forms a 

 liquid bisulphite compound, and which agrees somewhat closely with the tetra- 

 hydrocuminal isolated by Schimmel & Co. from water fennel oil, and named by 

 them phellandral. (Die Aetherischen Oele, 2nd Edition, p. 449.) 



When thus prepared the analytical figures for cryptal were in agreement 

 with the C I0 H I6 molecule, and the molecular refraction worked out almost 

 theoretically, a result not so far obtained with the other aldehydes of this group 

 occurring in Eucalyptus oils. 



Cuminal does not contain an asymmetric carbon atom, consequently 

 it is optically inactive. Aromadendral evidently exists in both optical 

 rotatory modifications, although, so far, the dextro-rotatory form has not 

 been isolated. Cryptal also shows irregular optical rotations when isolated from 

 the oils of different species, so that probably both forms of this aldehyde 

 also occur. 



This irregularity in optical rotations is indicated from the results obtained 

 with the oils of species in which these aldehydes are pronounced, and the crude 

 oils' and fractions of the following species show this clearly. 



The oil of Eucalyptus hemiphloia, New South Wales, distilled in September, 

 gave the following results : — ■ 



Crude oil ... ... ... ... ... ... ... a D 



Fraction boiling below 183 C. ... ... ... ... ,, 



between 183-215° C. ... ... ... 



2I5-230°C. ... ,, 



The oil of Eucalyptus aliens, New South Wales, distilled in June, gave :— 

 Crude oil ... ... ... ... ... ... ... a D — 6-5° C. 



Fraction boiling below 183° C. ... ... ... ... ,, — 5-6° C. 



between 183-225 C. ,, — 6-o° C. 



225-255°C , ■ ■ 14-6° C. 



The oil of Eucalyptus salubris, Western Australia, distilled in July, gave : 



Crude oil a a — ■ 5-8° C. 



Fraction between 168-172 C + 6-8° C. 



„ 172-183° C + 0-5° C. 



„ i8 3 -2i 9 C 8-9° C. 



219-240 C ,, • - 30-1° c. 



The oil of Eucalyptus rostrata, South Australia, distilled in June, gave : — 

 Crude oil ... ... ... ... ... ... ... a D — 12-4° C. 



Fraction between 173-188 C. ... ... ... ... ,, — 7-5° C. 



„ 188-255° C • - - 21-2° C, 



