597 



that no advantage is gained by prolonged distillation. The 

 oil contains but a trace of acid, and as the amount of ester 

 is also very small, there is nothing to attack the metal of 

 the still, and consequently the crude oil is but slightly 

 coloured. The low boiling aldehydes are also only present 

 in traces, so that the crude oil is practically free from these 

 somewhat objectionable constituents. As this Melaleuca 

 only grows as a shrub or small tree, the material for distil- 

 lation would be easy to collect, and consequently could be 

 distilled at a very cheap rate, especially as it yields such 

 an abundance of oil. 



The leaves of the Port Macquarie trees are generally 

 more robust looking than those of the Queensland 

 material, and this might be thought to be due to the 

 southern location of the New South Wales plants; but there 

 is possibly another explanation, and that is the stimulating 

 effect of an increased amount of manganese in the leaves 

 of the southern trees over those of Queensland. Just what 

 part manganese plays in the economy of plants is not yet 

 known, but it is now shown to be a very constant constitu- 

 ent in the ash of those Australian trees so far tested, 

 particularly in the Coniferae. The quantitative determin- 

 ation of the manganese in the ash was carried out by boil- 

 ing 0"03 gram, with lead dioxide and nitric acid as described 

 in our " Research on the Pines of Australia," page 83, 

 where this matter is somewhat fully dealt with. The 

 amount of Mn. in the dark brown ash of the leaves alone of 

 the New South Wales Melaleuca was 0*166^, and in the 

 ash of the leaves alone of the Queensland sample it waw 

 0*047^, or more than three times as much in the New South 

 Wales material. In the woody twigs of the Queensland 

 plants, without the leaves, the amount of Mn was 0"037f . 

 Whether an increased amount of manganese is partly 

 responsible for the increased yield of oil is a question yet 



