June 1, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
9G5 
SOME EXPERIMENTS ON SULPHITE OF 
MAGNESIUM. 
BY n. H. DAVIES, BELL SCHOLAE. 
Some discussion lias recently taken place as to 
tlie composition and properties of sulphite of mag¬ 
nesium; I have, therefore, at the request of Dr. 
Tilden, undertaken a few experiments upon the 
matter. 
Sulphurous acid gas, prepared by the action of 
copper on sulphuric acid, was passed, after being 
carefully washed, into water holding in suspension 
some ordinary carbonate of magnesium. The latter 
rapidly dissolved with effervescence, and the current 
of sulphurous acid gas was maintained until it ap¬ 
peared to be no longer absorbed, and the crystals 
first formed had re-dissolved, yielding a clear liquid. 
This solution was strongly acid to test paper; had a 
powerful odour of sulphurous acid, and, when 
shaken in a bottle, gave off that gas freely. A por¬ 
tion of this was submitted to analysis. 
(1) . 1*4175 grin., largely diluted with well-boiled 
water, required 50-45 cub. centim. volumetric solu¬ 
tion of iodine (containing F27 grm. iodine in 100 
c.c.) = 12*74 per cent, of SO s . 
(2) . 2*809 grins, required 112*8 c.c. of the same 
volumetric solution of iodine=12*85 per cent, of S0 2 . 
(3) . 18*3695 grins., oxidized by means of potassic 
chlorate and hydrochloric acid, yielded 8*0005 grms. 
BaS0 4 , corresponding to 
2*3805 grms. SO„, or 12*95 per cent. S0 2 . 
(1). 10*875 grms., treated with a strongly acid solu¬ 
tion of BaCL, gave a precipitate weighing TT12 grm., 
corresponding to ‘230 per cent. S0 2 . This existed 
as sulphate, and must therefore be deducted from the 
whole number found in the previous experiment. 
This will leave 12 7 2 per cent, of S0 2 existing as 
sulphite, and this result agrees closely with the 
numbers obtained by volumetric estimation. 
(5). 19*539 grms. were evaporated slowly to dry¬ 
ness, and the residue strongly heated. It yielded 
3*09 per cent. MgO. 
The amount of sulphur found as sulphate would 
require *14 of this MgO, leaving 2*95 per cent, com¬ 
bined as sulphite. 
If this be combined as acid sulphite (or bisulphite) 
having the formula MgH 2 2S0 3 it will require 9 44 
per cent, of S0 2 , thus leaving 3*33 per cent, of gas 
free. 
Summary of results . 
1. 2. 3. 4 Mean. 
MgO. 2*95 2*95. 
S0 2 . 12*74 12-85 1-2*72 12.77. 
Ratio of MgO to S0 2 found — 1 : 4*32. 
,, according to formula MgH 2 2S0 3 = 1: 3*20. 
It will be observed that the proportion of S0 2 to 
MgO is rather greater than would be required, sup¬ 
posing the solution to contain an acid sulphite of the 
formula MgH 2 2S0 3 . 
A portion of the above solution was slowly evapo¬ 
rated by simple exposure to the air. In this way 
crystals were deposited in about a week, which were 
found on examination to consist wholly of sulphate ; 
oxygen had been absorbed from the air. 
Another portion of the solution was evaporated 
at a gentle heat on a water-bath, and the deposited 
crystals collected, drained, slightly washed, and dried 
by exposure to the air. Analysed, they yielded as 
follows : 
Thied Series, No. 101. 
(1) . *3385 grm. required 31*3 c.c. vol. sol. iodine = 
29*59 per cent. S0 2 . 
(2) . *2415 grm. required 22"5 c.c. vol. sol. iodine = 
29*81 per cent. S0 2 
(3) . -47 5 grm. gave on ignition ’089 grm. MgO = 
18*73 per cent. MgO. 
Summary of results. 
Theory. 1. 2. 3. Mean. 
MgO.18-80. 18-73. 18-73. 
S0 2 . 30-18 29 59. 29-81. 29*70. 
The numbers in column headed “ Theory ” are 
those obtained by calculation from the formula of 
neutral sulphite MgS0 3 0H 2 O. 
The crystals sent to the museum by Dr. Archbold 
have precisely the same appearance as those ana¬ 
lysed by me, and present the same reactions. They 
are neutral to test paper. 
Dr. Tilden lias furnished me with the numbers he 
obtained in the analysis of this specimen. 
(1) . -207 grm. took 19 c.c. vol. sol. iodine =29*37 
per cent. S0 2 . 
(2) . *506 grm. yielded -096 grm. MgO = 18*97 per 
cent. MgO. 
It appears from the above detailed experiments 
that the salt noticed by Dr. Archbold in the paper 
he communicated to the Pharmaceutical Journal 
a short time ago, is incorrectly described by him as 
the “Bisulphite of Magnesia,” if by this name he 
wishes to indicate the acid sulphite of magnesium. 
The formula of that salt, if procurable in the 
crystalline form, would be MgH 2 2S0 3 , and not as 
he mutes it Mg 2S0 3 . 
But it has been already pointed out that it is 
highly improbable that such a compound can exist 
otherwise than in solution. It might as reasonably 
be expected that “Fluid Magnesia” would, on 
evaporation, yield crystals of the hydric or bicar¬ 
bonate ; but, as is well known, the crystals which 
are frequently met with in fluid magnesia are not 
bicarbonate, but simply normal carbonate, with three 
molecules of water of crystallization—MgC0 3 3H 2 0. 
In order to test further the possibility of producing 
crystallized bisulphite of magnesium, I intend. to 
try the effect of exposing a saturated acid solution 
of magnesium sulphite to a low temperature. It is 
just possible that this compound, which I have shown 
cannot be procured according to Dr. Archbold’s 
directions, may be obtained by tills modification of 
the experiment. 
EXTRACT OF MEAT. 
BY P. MULLER,* 
Doeteur cn Medecine de la Faculte de Paris. 
Various concentrated preparations of meat have 
now for some years been used for the purpose oi 
alimentation, and more particularly by medical men 
who have prescribed them in cases where the 
stomach has refused to receive ordinary food, or 
where they have sought to restore the powers ot 
convalescent patients. The author, however, con¬ 
siders that there is considerable misunderstanding in 
reference to the properties of these extracts, and in 
the course of a lengthy memoir, from which we can 
* Abstracted from a memoir by the author, published in 
the Moniteur Scientifque, vol. iii. p. 011. 
