107 
amalgam of sodium for the production of hydrogen. When 
doing this it was found that the amalgam had become one 
mass of crystals. These crystals are fine needles or prisms of 
considerable length ; some may be traced in the tangled mass 
for about half an inch; they present hollow ends, although it 
was not possible to trace this hollowness through the whole 
length of the crystals. They are hexagons, and contain 9'47 
per cent of sodium ; an excess of mercury remains ; 103 
per cent would be equal to 2 at. of mercury and 1 of 
sodium. He had not seen any notice of an amalgam 
of similar composition. It can be examined only through 
glass, as it rapidly absorbs oxygen from the moisture 
of the air, and cannot be retained in the air many seconds 
without change being perceived. If this change be examined 
under a microscope, bubbles of hydrogen are seen to rise from 
every corner, extremely minute certainly, so that many 
millions would be required to cover a square inch, but affording 
one of the most convincing and direct proofs of the existence 
of moisture. This property may in many cases be found to 
be of value. The inclination to combine with oxygen when 
dry seems comparatively slight. 
Dr. Smith mentioned also a method of separating lime 
from phosphoric acid, which, as far as he was aware, was 
new. Many very elaborate methods had been given. After- 
adding tartaric acid to a solution of phosphate of lime in 
muriatic acid, the lime may be precipitated by oxalate of 
ammonia and ammonia as in other solutions. Carbonate 
of lime has been obtained in this way free from every trace 
of phosphate, and the solution has been freed entirely from 
lime. Tartaric acid prevents the precipitation of phosphate 
of lime in weak solutions by ammonia, but has no influence 
over the oxalate of lime. The true action of tartaric and 
similar acids in preventing precipitation deserves a more 
careful inquiry than has yet been made. 
