508 Prof. G. Gulliver on Raphides. 
XLIX.—Observations on Raphides. 
By Georce Gutiver, F.RS. 
[Continued from p. 409.] 
Their Chemical Composition.—Since the observations of Ras- 
pail and Edwin Quekett, raphides have generally been regarded 
as composed of phosphate of lime, and many spheraphides as 
oxalate of that earth. But, in the ‘Trans. Edin. Bot. Soc.’ for 
1861, Prof. Douglas Maclagan gave an analysis of the raphides 
of Richardia, from which it results that these are composed of 
the oxalate. Hence further observations seemed so desirable on 
the subject, that Dr. Davy kindly undertook, at my request, the 
examination of several specimens which I sent to him; and, with 
his permission, the following notes of his experiments are here 
published :— 
“Owing to the minute quantity of matter in the raphides or 
other crystals (minute even in relation to the quantity of ash 
afforded by the leaf or other vegetable structure), there is diffi- 
culty in coming to more than a proximate conclusion as to their 
composition. It is not improbable that, in some instances, it 
is composite, consisting, for example, of oxalate of lime and 
magnesia. Possibly vegetable matter may influence the reagents. 
In the scales of the onion, I found the precipitate from an acid 
solution, by ammonia in excess, in the form only of minute 
well-defined crystalline globules. Raphides may generally con- 
tain a little vegetable matter, in consequence of which their 
forms, though somewhat altered, remain after the matter which 
is soluble in an acid (such as phosphate of lime), or is in part 
fixed after combustion (such as the lime of the oxalate), is re- 
moved. 
“. Officinal Iris Florentina contains a good deal of lime. Its 
white ash consists chiefly of lime, and, strongly heated, emitsa 
brilliant white ight. The ash contains a small proportion of — 
phosphate of lime, but a much larger of carbonate. From the — 
crystals resisting the action of dilute acetic acid, I infer that 
they are of oxalate of lime. They are rapidly dissolved by strong _ 
nitric acid, and some by acetic acid, without effervescence. ‘ 
2. Mesembryanthemum muricatum is readily incinerated (the 
leaves more readily than the stalk) ; it yields a good deal of © 
white ash, retaining the form of the leaf, but shrunken. Ignited, — 
it shines with a bright yellow light, that of the stalk with a red 
light. The raphides, I infer, are composed chiefly of oxalate of 
lime and magnesia, with perhaps a little silica, the magnesia in 
rather larger proportion than the lime. They are not dissolved in — 
dilute acetic acid. The leaves, under the action of dilute muriatie 
acid, give up the greater portion of their saline and earthy 
