10 



BULLETIN 44:?, TT. S. DEPARTMENT OF AGRTCUT.TUEE. 



results. This would indicate that high citral content can be secured 

 only from plants grown on very well drained soil. 



TiTYie of harvest. — Although the citral content of the oil does not 

 appear to be greatly affected by the time of harvest, the results indi- 

 cate that of the two harvests each year the oil distilled from plants 

 of the first harvest contains the greater quantity of citral. Data 

 covering a number of years are given in Table V. 



Table V.- 



-Citral content of lemon-grass oil distilled from plants hai'vested at two different 

 times of the year. 



Year and plants har- 

 vested. 



Citral content of oil. 



Year and plants har- 

 vested. 



Citral content of oil. 



First 

 harvest. 



Second 

 harvest. 



First 

 harvest. 



Second 

 harvest. 



190S. 



Per cent. 

 72 

 74 

 75 



76 

 78 



78 



78 

 77 



Per cent. 

 74 



72 

 72 



78 

 76 



1914— Continued. 

 No. 8 



Per cent. 

 81 



75 



70 

 73 



77 

 78 

 80 

 80 

 81 

 85 



Per cent. 

 72 





No. 9 



59 



Third plat 



1915. 

 No. 5 





1912. 



68 



No. 1 



No. 6 



71 



No. 8 



No. 8 



64 





No. 9 



70 



1914. 



No. 10 



74 





No. 11 



82 





No. 12 







76 

 79 







No. 13 



















SOLUBILITY OF LEMON-GRASS OIL IN ALCOHOL. 



For many years it was considered that good lemon-grass oil should 

 be soluble in clear solution in three volumes of 70 per cent alcohol, 

 and this was the test applied before the method of citral determina- 

 tion was in general use. It served a useful purpose, however, inas- 

 much as certain adulterations which had become quite general could 

 thus be detected, but at the present time, when the valuation of the 

 oil is entirely on the basis of the citral content, it is difficult to under- 

 stand the reason for the continued use of the solubility test. It 

 has been shown repeatedly that in many parts of the world pure 

 lemon-grass oil does not pass the solubility test, especially after it 

 has been stored for several months. This has been true of most of 

 the samples of the oils produced in the Western Hemisphere, so that 

 West Indian lemon-grass oil has come to be a synonym for insoluble 

 oil. This discrimination has kept out of the market inany West 

 Indian oils of very high citral content. 



There has been much discussion regardmg the factors which affect 

 the solubility of the oil, it having been contended that the length of 

 time of distillation is the controlling factor. In order to secure data 

 upon this point the following tests were made: In 1914, 158 pounds 

 of the freshly cut plants were distilled with steam and the oil drawn 



