to the Earthy Constituents presented to their Absorbing Surfaces. 255 
notes, I will in the first instance refer to one made in 1827, in which grasses 
and trefoils of various kinds, which had been watered from time to time with 
a solution of nitrate of strontian, were found on examination to possess no 
trace of this earth *. 
In the above instance, however, as the plants had grown in common garden 
mould, all that could.be inferred was, that when lime and strontian are both 
presented in a state of solution to their roots, they select the former, and reject 
the latter. 
In 1829, the seeds of various plants, such as the garden radish (Raphanus 
sativus), the cabbage (Brassica oleracea), the garden bean (Vicia Faba), hemp 
(Cannabis sativa), &c., were sown in soils containing various proportions of 
sulphate of strontian, with or without manure, and amongst the rest, one in 
which no other ingredient, except this earth, was present in any quantity. 
The plants grew up, and when they had arrived at maturity, were collected, 
burnt, and their ashes examined. No strontian, however, could be detected 
in any one of them, not even in that where the matrix consisted almost wholly 
of the earth in question. 
In 1831, the experiments were conducted with rather more attention to 
* I will state, for the satisfaction of chemists, the method I pursued to determine whether strontian 
was or was not present. , e 
After washing off the alkaline salts from the ashes by lixiviation in warm distilled water, I Í dipsitda 
the residuum in diluted nitric acid. This first acted upon the earthy carbonate, and afterwards upon 
the earthy phosphate. The solution in nitric acid consequently contained both. The phosphate being 
thrown down by ammonia, the nitrate remaining in solution, rendered exactly neutral, was evaporated 
by a heat never exceeding 212°, in a flask, and when dried, the mouth of the vessel was closely stopped 
by a cork. When cold, alcohol of the sp. gr. of *815 was poured upon it, which would dissolve all 
the nitrate of lime. If there was no undissolved residuum, the absence of strontian from this portion - 
of the ashes might be fairly inferred. If there was any, I generally digested it with a solution of car- 
bonate of soda, and after filtering, heated the earthy residuum in a covered capsule, so as to expel the 
carbonic acid. A small quantity of distilled water would then generally dissolve the whole; and if 
the addition of a drop or two of sulphuric acid to this solution did not render it turbid, I felt myself 
justified in concluding that no strontian was present. The precipitate, if any, was concluded to be 
sulphate of strontian. 
A similar procedure was adopted with reference to the earthy phosphate, and likewise to that por- 
tion of the ashes which remained undissolved by the nitric acid upon its first application. In both 
cases, digestion with an alkaline carbonate reduced the earthy matter to a fit condition to be acted 
upon by nitric acid, and the subsequent steps pursued to determine the presence of strontian in it 
corresponded with those already detailed. 
