230 Transactions of the Royal Microscopical Society. 
powder, which is easily soluble in warmed alcohol. The simplest 
way, however, that I find to treat the leaves, is either to make 
several solutions from the first one, and thereby reduce the quantity 
of wax in each, or else to allow the solutions to stand for a few 
hours in test tubes ; a precipitate is then formed, and the clear 
portion can be drawn off for examination by means of a glass 
siphon, when a few more drops of alcohol, which has been pre- 
viously warmed, should be added to that drawn off, so as to prevent 
any further precipitation from taking place. This latter method is, 
of course, unavailable for any definite form of analysis, as much wax, 
starch and gum, &c., are held in solution ; by its means, however, 
the xanthophyll bands in the blue are more resolved, from what, 
as in Fig. 2, was but a general absorption ; the spectrum also, as 
is seen on referring to Fig. 4, is much fighter in the spaces, and 
the hands are intensified and more defined. 
Among the other carbonaceous compounds that exist in the 
leaves of laurel, besides all evergreens to a more or less extent, is 
oil. It is of a brownish tint, has an aromatic smell, and is obtained 
from the berries by distillation. I have, however, procured it from 
the leaves by the following method : 
Into a test tube containing an alcoholic tincture prepared from 
laurel leaves, I dropped clarified castor oil, which at once formed a 
copious thick green precipitate. Oil was added in each case, till no 
further precipitation took place, when the whole was tested with 
another solution in alcohol, to see that no excess of castor oil had 
been added ; it was then allowed to stand for a few hours. The top 
solution was then carefully siphoned off, care being taken to exclude 
any of the precipitate. That drawn off was of the colour of very dark 
sherry, and was very oily. After being allowed to stand for twelve 
hours, a weak solution of sulphuric acid was added ; this caused a 
precipitate of a greenish tint. I allowed this to settle entirely, and 
then holding the tube in a vessel of hot water, I added more acid 
till no further precipitation took place ; the whole was then allowed 
to simmer gently for a few minutes, when it was removed from the 
tube by means of a siphon as before, and carefully examined by the 
micro-spectroscope, the measurement and spectrum of which I have 
given in Fig. 5. 
Fig. 5. 
M. 
A. 
Obs* rvations. 
1 I 23 ' 7 
1 \ 23-8 
2 22-05 
3 { 22 ' 8 1 
d 1 20-5 / 
Commencement 
End 
Centre 
Commencement 
676- 751 
666-75/ 
644-50| 
J592-25 
\515-50 
Class 2. Yery black, shaded to 
end ; size " 1. 
„ 1. Centre dark, ends shaded; 
size *1. 
^ black^'} General absorption. 
