1817.] Scientific Intelligence, 483 
V. Improvement in the Oxygen and Hydrogen Blow-pipe. 
(To Dr. Thomson.) 
SIR, Worcester, May 18, 1817. 
Having observed in your Journal some accounts of explosions 
taking place, even with Professor Cumming’s safety cylinder, from 
the frequency of the minor explosions forcing back the oil into the 
condensing cylinder, [ take the liberty of suggesting the expediency 
of placing a pipe of a zigzag form instead of that which commonly 
spmconnieates between the two cylinders, as in the following 
sketch :— 
A, the condensing cylinder. 8B, pipe of a zigzag form. C, 
cylinder with oil. D, Dr. Clarke’s fagot of brass tubes. 
3 I am, Sir, yours truly, 
Francis SPitsBury. 
VI. New Mineral Salt. 
Some weeks ago Mr. Heuland presented me with a specimen of 
a salt which had been brought to this country from Calatayud, in 
Arragon, by the Spanish Ambassador, and which he informed me 
was a compound of sulphate of soda and sulphate of magnesia. 
The specimen was remarkable for its beauty. The following de- 
scription will convey some idea of it to the reader :— 
Colour snow-white. It was about two inches long, of a fibrous 
texture, and had quite the aspect of fibrous gypsum. Each fibre, 
on examination, could be recognized as a four-sided prism, about 
two inches in length. The prisms were easily separated from each 
other. The specimen was visibly intersected by 21 divisions cross- 
ing the prisms at right angles, so that it had the appearance of 
being composed of 22 different layers or strata. Lustre shining and 
silky. ‘Translucent. Soft. Brittle. Very easily frangible. Spe- 
cific gravity 1°5577. Taste intensely bitter, Not altered by ex- 
posure tothe air. Very soluble in water. 
1. When heated, it dissolves readily in its water of crystalliza- 
tion ; and when exposed to a red heat, loses half its weight. 
2. Ten grains of it were dissolved in water, and precipitated by 
muriate of barytes. The sulphate of barytes formed weighed 9°8 
‘grains; indicating 3°32 grains of sulphuric acid. 
3. Ten grains were dissolved in water, and a solution of pure 
soda was mixed with it. he magnesia precipitated being separated 
by the filter, and heated to redness, weighed 1°62 grains. 
2 weg 
