462 
LEEDS CHEMISTS’ ASSOCIATION. 
would make it against the interest of the maker to substitute soda for potash, that a 
third party has doubtless supplied him with an impure carbonate of potash. 
Processes for directly determining the iodide present:— 
1. By HgCl. Having given much time to this process, the author found that it 
usually gave hut 92 instead of 100, and finds a confirmation of his unfavourable opinion 
of the method in the fact that Fresenius does not give it. 
2. By PdCl 2 . Too costly. 
3. Oxidation and titration by Cl water. (Sutton’s Vol. Anal. par. 7G). Too compli¬ 
cated for practical use. 
4. Precipitate a strong solution by AgO,NO b ; wash, dry, and weigh, the mixed Agl, 
and AgCl. Determine chlorine separately and deduct. No sample gave less than 9G 
per cent, iodide. 
The conclusions from these experiments must be, that the salt now in the market was 
commercially pure. 
A discussion ensued, in which much satisfaction was evinced at the high degree of 
purity found. Mr. Ward moved, and Mr. Atkinson seconded, a vote of thanks to the 
author, expressing the hope that his example would induce other Associates to contri¬ 
bute papers. 
The Seventh Meeting for the Session was held on March 9th ; the President in the 
chair. 
Mr. R. H. Davis, of Harrogate, a corresponding member, read a paper upon “ The 
Value of the Marc left in the manufacture of Tincture of Opium.” 
The author noticed the discrepancy between the statement of Pereira, who says that 
he often prepared morphia from this marc, and that of Dr. Garrod, who did not detect it, 
and found that in doses of thirty grains it was inert. 
Experiments. The dried marc from three gallons of Tinct. Opii weighed thirteen and 
a quarter ounces, being the product of thirty-six ounces of opium in coarse powder. 
From this the morphia was very carefully extracted by processes which were fully de 
tailed, and the final result was fifty-six grains of pure hydrochlorate of morphia (= 
forty-two grains of morphia). 
The residue was treated for codeia, hut without success. 
The author said that he regarded two practical conclusions as being consequent upon 
the facts detailed, viz.:—1. That chemists who adopt percolation obtain a stronger tinc¬ 
ture than that of the Pharmacopoeia. 2. That it is worth while collecting the marc for 
the sake of the morphia. 
Mr. Rimmington (Bradford) and others took part in the discussion which followed. 
Mr. R. M. Atkinson read a paper upon “ Liquor Ammonias Acetatis, B. P.” He com¬ 
menced by an historical notice of the preparation, evincing much research amongst the 
writings of the early chemists. It was first introduced by Raymond Minderer in 1621. 
He orders strong vinegar to he saturated with spirit of hartshorn. The vinegar of that 
country and period (Germany) was probably made from grapes, and the alkali would be 
literally what its name imports. 
Attempts to prepare a concentrated solution by evaporating weaker ones have engaged 
the attention of many ; but the author showed that the salt volatilized at a little over 
90° F., and hence these essays were futile. The strength of the vinegar was some¬ 
times increased by freezing. The formulae used during the past two centuries in this 
and other countries were reviewed, and specimens exhibited prepared in accordance with 
some of these. 
Arriving at the process of the British Pharmacopoeia, Mr. Atkinson spoke with approval 
of the substitution of caustic ammonia for its carbonate. The specific gravity was now 
defined (LOGO), and every facility was given for making it correctly, as the acid was of 
commercial strength and the saturation no longer difficult. 
He thought Dr. Redwood’s allusions to the advantages of any carbonic acid present in 
the old preparation as being hypercritical. 
That we should have returned to the original process after 250 years’ wandering was 
singular and interesting. 
The thanks of the meeting were given to the authors of the papers. 
