258 PRINCIPLES OF BOTANY, ETC. 
as when lying in common water, they required from 
36 to 38 hours. Ina letter, dated February, 1801, 
he writes me, that in Vienna they found much be- 
nefit from the discovery of this fact, and that seeds 
twenty and thirty years old, brought from the Ba 
hama islands, Madagascar, &c. which constantly 
vefused to germinate, very readily, in this way, ve- 
getated, and produced plants which grew up very 
successfully. The Mimosa scandens, which as yet is 
not to be found in any botanic garden, grew very 
well with this acid. As every gardener cannot ob- 
tain the oxy-muriatic acid, Mr Humboldt proposes a 
very easy method to procure it without difficulty. | 
He took a cubic inch of water, a tea-spoonful of 
common muriatic acid, two tea-spoonsful of oxyd of 
manganese, mixed it and placed the seeds in them. 
The whole was now allowed to digest with a heat of 
18—30° Reaum. ‘The seeds all germinated beyond 
expectation. It is necessary to.take the seeds out, 
as soon as the corcle appears. ‘Uhat the seeds are 
not impaired by the acid, is proved by the many 
plants which have been treated in this way, under 
the inspection of Mr Jacquin, and in which vege- 
tation goes on wonderfully well, though many of 
them had their seeds steeped in the oxy-muriatic 
acid. 
It is the oxygen of the atmosphere which stimu- 
lates the seed to germination. And this circum- 
stance explains at once the experiment of Mr Achard, 
why plants vegetate faster in very compressed air, 
than in air in its common state. 
Besides 
