December 2,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
441 
THE ACTION GE NITRIC ACID UPON 
NATAL ALOES. 
BY WILLIAM A. TILDEN, D.SC., F.C.S. 
In tlie course of reading the interesting paper of 
Professor Fliickiger upon the “ Crystalline Prin¬ 
ciples in Aloes,” presented at the last meeting of the 
British Pharmaceutical Conference, and recently 
published in the Pharmaceutical Journal, I was 
struck with.one statement which appeared to me ex¬ 
traordinary. It was to the effect that his “nataloin,” 
when treated with nitric acid, yielded nothing hut 
oxalic acid, and that though sought for, picric and 
chrysammic acids were not to he found. I regard 
the aloins as bodies belonging to the class called 
phenols,—in fact, a land of orcin, though unquestion¬ 
ably of a complex and highly condensed type. It 
therefore, seemed to me improbable that nataloin, 
whilst agreeing with other substances of the same 
family in general characteristics, should so far differ 
as not to give a nitrated acid of some kind. I there¬ 
fore procured a small quantity of Natal aloes, and 
prepared from it the crystalline principle according 
to Fliickiger’s- directions. Flis description of the 
physical characters of this substance appear to be 
correct. Three grams of perfectly pure nataloin, 
■which had been several times crystallized from 
rectified spirit, were dissolved in about ten cubic 
centimetres of pretty strong nitric acid, and, when 
the first violent action was over, the now orange- 
coloured liquid was digested in a flask for two or 
three hours, it was then turned into a dish and 
evaporated to dryness. A mass remained, which 
was evidently chiefly oxalic acid, but was tinged 
intensely yellow; it was put back into the flask with 
a small quantity of fuming nitric acid (sp. gr. P45) 
and warmed gently till all action seemed to be at an 
end. The liquid was once more evaporated to dry¬ 
ness. On treating the residue with water it gave a 
solution of a bright golden colour, which dyed silk 
yellow. Warmed with cyanide of potassium, it gave 
a blood-red liquid, and, when boiled with chloride of 
lime cliloropicrin, unmistakable from its frightful 
odour, was evolved. Shaken with lime and ferrous 
sulphate, a red liquid was produced. The remainder 
of the residue was mixed with solution of potassic 
acetate and allowed to stand; next morning tufts of 
orange needles were deposited. These were found 
to be explosible, and when boiled in water and mixed 
with ammoniacal cupric sulphate, the characteristic 
green precipitate changing, on boiling, into yellowish 
scales was produced. These reactions indicate, be¬ 
yond doubt, the formation of picric acid , but as Iliad 
not enough material from this experiment to analyse 
one of tlie salts, I treated some of the crude drug 
with nitric acid. This requires some caution, as 
with nitric acid of sp. gr. 1*37 the action is very 
energetic, and a great deal of frothing occurs in the 
early part of the process with production of a large 
quantity of a ruby-red resinous substance. When 
this, however, is digested for some time with nitric 
acid, assisted, towards the end, with a little fuming 
nitric acid, an oily substance results, which solidi¬ 
fies, on cooling, into crystalline masses. These 
treated with boiling water dissolve, forming a bright 
yellow bitter solution, which, after neutralization 
with potassic carbonate, deposits, on cooling, a mag¬ 
nificent crystallization. These crystals are but 
slightly soluble in water, but may readily be crystal- 
Third Series, No. 75. 
lized from boiling water. Long lustrous prisms are 
then obtained, which present all the appearance and 
characters of potassic picrate. Analysed, *5420 
gram dried at 230° F. gave T735 of potassic sul¬ 
phate, which corresponds to 14*33 per cent, of po¬ 
tassium. Ticrate of potassium, C 6 H 2 (N 0 2 ) 3 K0, 
contains 14 (40 per cent, of potassium. 
The action of nitric acid upon nataloin yields, 
therefore, both oxalic and picric acids. 
A CHAPTER IN MICROSCOPY. 
BY HENRY POCKLINGTON. 
The author of a certain book on the microscope 
tells a tale of a person who purchased a first-class 
microscope from one of the then principal manufac¬ 
turers in London, but a few days after desired to 
return it, with the remark that he had tried it and 
found it perfectly useless, because it would not even, 
show the crystals of sugar. In reply to an interro¬ 
gation as to how much he had tried to look at, he 
said, “ Oh, a good big lump from the sugar basin! ” 
However much an experienced microscopist may be 
disposed to laugh at such crass ignorance of the 
proper way of using the microscope, the purchaser 
was to be pitied if he had become the possessor of a 
costly instrument without having the least notion as 
to how the thing was to be used, or for what pur¬ 
pose its several parts were designed. And there is 
no doubt, that amongst the many possessors of an 
instrument which now bids fair to be as fashionable 
a piece of furniture in a well-to-do household as a 
pianoforte, there are many whose ideas of how to 
use it are in a state not so unlike that of our lumo- 
A. 
sugar friend, and who may not be indisposed to he 
thankful for a few hints as to what to do and what 
not to do. 
The initial difficulties in the use of the microscope 
are not very great; a few minutes, or, at any rate, 
hours, will suffice to overcome them. In the higher 
walks of microscopy the case, as we shall see later 
on, is somewhat different. But as the tyro must 
walk before he can climb, he need not trouble him¬ 
self by looking so far ahead. 
We will assume that the microscope has Been 
purchased :* not a big showy stand unfit for rough 
every-day work, but such a student’s as any maker 
will sell nowadays for 4*5, 410 or 420, according to 
the apparatus ^required therewith: and has been 
brought home, unpacked, and the happy purchaser 
only too anxious to delight the eyes of his wife with 
the wonderful “revelations of the microscope.” He 
will probably have learned the names of its severe 1 
parts, and how “to put them together.” At all 
events, he ought to get this much information from 
the maker of the instrument, and to be prepared 
to listen to us with his microscope en regie. 
The first question to consider is that of the light 
to be used. Books are agreed as to this. Daylight 
being, according to them, by far preferable to any 
artificial light; yet, by far, the majority of micro- 
scopists use artificial light for their researches,— 
partly from compulsion, because their day-time is 
occupied by other pursuits, called by a microscopical 
friend butter-bread business, but also because a 
* Big microscopes are not to be despised by those who can 
afford them, and who range the higher fields ot research. 
Our remarks apply only to beginners. 
