19S 
TINCT. OPII, B. P. 
4k • 
scopic characters, but belong to the class which have been designated in these 
papers as “ watered” or “smoked,” are found to give with reagents highly cha¬ 
racteristic appearances. This statement rests mainly on repeated experiments 
with morphine. 
11. That in the choice of reagents care should be taken to avoid such saline 
solutions as give variable crystalline deposits ; and that in any case we should 
avoid confounding the crystalline forms proper to the reagent with those due to 
its action on the sublimate. 
12. That the results obtained by sublimation, in the case of the alkaloids and 
analogous active principles, are not more subject to failure than other tests; 
that several of the reactions are remarkable for delicacy, constancy, and cha¬ 
racteristic appearances, and greatly surpass in beauty and distinctness those ob¬ 
tained with deposits of equal weight. 
Before I conclude I must again refer to Dr. Helwig’s work as the first-pub¬ 
lished treatise on this interesting subject. I have endeavoured to do justice, 
both to his originality and to the careful industry which he has displayed. 
But, on referring to my former communication (No. III.), m which I said 
that he had figured the crystals of nitro-prusside of sodium as a reaction of a 
solution of this salt with morphia, I find that I omitted to state that, in many 
passages of his work he shows himself quite alive to the necessity of distin¬ 
guishing the crystalline forms of reagents from the results of their action on the 
sublimates, and that he is well acquainted with the forms in question. If, in 
any other point I have not done him justice, the explanation of the omission 
must be sought for in the difficulty of finding, on reference to so considerable a 
work, the precise passage which would have established his claim to priority. 
On the whole, my own experiments have strikingly confirmed the results at 
which he had arrived. When our statements do not coincide, their divergence 
may be reasonably traced to the difference in our methods of procedure. It 
ought, however, to be understood that I have not contented myself with verify¬ 
ing the contents of Dr. Helwig’s work ; but have shown that the method of 
sublimation admits of a wfider application than he has given it, and that many 
questions of great practical value were left untouched, upon which some light 
lias been thrown by the experiments described in these pages. 
TINCT. OPII, B.P. 
The result of a careful examination of several samples of this tincture proves 
its present very untrustworthy character, and how important it is for pharma¬ 
ceutists to strictly follow the directions of the Pharmacopoeia, so as to ensure a 
more reliable preparation. The Pharmacopoeia directs the tincture to be made 
by macerating one ounce and a half of powdered opium in a pint of proof spirit. 
If we therefore take the average percentage of morphia in powdered opium to be 
10, and extractive matter to be 62, the percentage of morphia in ordinary moist 
opium being 8, extractive 50, and moisture about 20, and supposing the proof 
spirit to dissolve al] the morphia, which is exceedingly doubtful,—a pint of B. P. 
tincture should yield nearly 407 grains of extract, and 65 grains of morphia. 
The following table shows the result of the analysis of four samples of tinc¬ 
ture purchased as “ Br. Ph. 1867 — 
Grains of Morphia in Grains of Extract in 
No. 20 fluid ounces. 20 fluid ounces. 
1.11.200 
2 .15.335 
3 . 26 . 365 
4.31-3.423 
