Biograpliical Account o/Dr. Wollaston, hy Dk, Thomas Thomson. 143 



on which account it got the name of uric acid calculus. Dr. Wollaston 

 analysed 4 new species of calculus, and determined the composition. 

 These were : — 



1. Fusible calculus. This calculus before the blow-pipe fused into an 

 opaque white glass. It is a mixture of phosphate of lime, and ammonia- 

 phosphate of magnesia. 2. Mulberry calculus. — So called by surgeons 

 because it has a brown uneven surface, having some resemblance to a 

 mulberry. It consists essentially oi oxalate of lime. 3. Bone earth cal- 

 culus. It has a brown colour and a smooth surface. It consists essen- 

 tially of phosphate of lime, and differs from bone earth by containing no 

 carbonate of lime. 4. In 1810 Dr. Wollaston discovered a new calculus, 

 to which be gave the name of cystic oxide calculus. 5. Gouty concre- 

 tions, composed of urate of soda, 



8. Such is a meagre catalogue of Dr. Wollaston 's chemical papers pub- 

 lished in the Philosophical Transactions ; there is still another notice by 

 him which deserves to be stated. 



Dr. Marcet, at the time of his death, was occupied with a set of experi- 

 ments to determine the quantity of salt in the Mediterranean sea, and with 

 endeavouring to account for the constant influx of the Atlantic ocean by the 

 straits of Gibraltar, without any sensible increase of the specific gravity. 

 He had applied to Captain William Henry Smyth, who was engaged in 

 surveying part of that sea, to supply him with water at great depths from 

 that sea. Dr. Marcet dying before he received the water expected. Cap- 

 tain Smyth gave to Dr, Wollaston three bottles from the bottom of the 

 sea, and at different distances from the Straits of Gibraltar. The first 

 two specimens were taken from 680 miles, and 450 miles from the Straits, 

 at the depths of 450 and 400 fathoms, contained water of the usual 

 specific gravity, namely, 1-0294 and 1.0295. But the third, taken 50 

 miles from the strait, and at a depth of 670 fathoms, had a specific gravity 

 of 1-1288. The first two contained 4 per cent, of salt, the last 17-3 per 

 cent. It is clear from this, that an under current outward, if of equal 

 breadth and depth with the current inward at the surface, would carrv 

 as much salt below as is brought in above, although it moved with \ part 

 of velocity, and would thus prevent any increase of salt in the Mediter- 

 ranean beyond what exists in the Atlantic. 



The remaining papers by Wollaston in the Philosophical Transactions, 

 amount to 25. They are on various subjects, all ingenious, and each 

 containing a new fact. 



Dr. WollastorCs Papers in rhilosophical Transactions. 



1. On Gouty and Urinary Concretions, vol. 87, p. 386, 1797. 



2. On Double Images by Atmospherical Refraction, vol. 87, p. 239, 

 1800. 



3. ICxperiracnts on the Clicmical Production and Agency of Electri- 

 city, vol. 87, p. 427, 1801. 



