26 
ON A NATURAL FORMATION OF CARBONATE OF SODA. 
tamed is to be filtered and evaporated until extract begins to deposit on the 
bottom of the dish, which will occur when the solution has been reduced to 
about ten fluid drachms. When cold this solution is to be passed through a 
small filter, and is then ready for the paper. This may be thin writing paper, 
the size contained in which has been removed by boiling* ; it should be immersed 
in the solution four times, and be allowed to drain and dry between each immer¬ 
sion. Of paper thus prepared, a piece measuring ^th of an inch square placed 
within the lower eyelid commences to act in about twenty minutes and continues 
to produce its effect during several hours. Its presence in the eye occasions no 
uneasiness beyond that which is attributable to the drug. 
A solution of the extract of Calabar Bean in glycerine made in the proportion 
of 2£ grains of extract in 100 minims of pure glycerine, has also been tried and 
found to answer well, the glycerine in no way interfering with the action of the 
extract. 
Further experiments may suggest still better preparations: for some hints 
respecting those here mentioned and for numerous careful observations upon 
them, I have to thank Mr. Charles John Workman of the Royal London 
Ophthalmic Hospital, Moorfields, and Mr. Bader of Guy’s Hospital. 
ON A NATURAL FORMATION OF CARBONATE OF SODA. 
BY R. HAINES, M.B., PROFESSOR OF MATERIA MEDICA, GRANT COLLEGE, BOMBAY. 
Some months ago a substance was brought to my notice by the Curator of the 
Economic Museum in this town, Dr. Bird wood, said to be a natural product of 
the neighbourhood of Aden, and to be used only for mixing with and imparting 
pungency to snuff. It consisted of irregular, nearly colourless, partly crystalline 
masses, composed apparently of two distinct portions: one was a brilliant, con¬ 
fusedly crystalline mass, amongst which the angles of cubical crystals could be 
observed ; the other, which seemed to be the upper portion, was a wdiite amor¬ 
phous substance, of a greasy feel, and rather strong soapy odour, very similar to 
that of crude borax. By taking portions of a number of lumps, and pounding 
the whole together, a fair average sample was procured. 
Dissolved in water, a colourless solution was obtained, alkaline to test-paper, 
and effervescing strongly with acids. Supersaturated with nitric acid, it yielded 
an abundant precipitate with nitrate of silver, a scanty precipitate with chloride 
of barium, and a slight crystalline precipitate, after some hours, with ammonia 
and phosphate of soda. A concentrated solution gave no precipitate with chlo¬ 
ride of platinum and alcohol. The dry salt being rubbed with sulphuric acid, 
and then with alcohol, did not impart to the flame of the latter the slightest 
tint of green. From these experiments it appears that the salt consists of carbo¬ 
nate of soda and chloride of sodium, with traces of sulphuric acid and magnesia, 
but that it contains neither potash nor boracic acid. * 
8-668 grammes, dissolved in water, left an insoluble residue of fine sand, 
weighing -377 grammes, equal to 4-35 per cent. The filtrate was made up to 
100 cubic centimetres. Of this, 10 cubic centimetres required for neutralization 
of Mohr’s normal acid 8-35 cubic centimetres, equivalent to -1837 grammes of 
carbonic acid, and to -44255 grammes of dry carbonate of soda. 50 cubic centi¬ 
metres of the filtrate were therefore equivalent to -9185 grammes of carbonic 
acid, and the whole 100 cubic centimetres to 4-4255 grammes of dry carbonate 
of soda, or 51-05 per cent. 
* Mr. Streatfeild recommends green paper, as white paper when soaked with tears is not 
always easily distinguished from the conjunctiva. 
