SEA SAND. 
55 
We have therefore tried to determine the limestone by an 
indirect method, measuring in a Hempel burette the volume of 
carbon dioxide gas, produced during effervescence. From a 
few rough experiments it appears that about T U of the sand is 
limestone. 
It was Mr. Edward Worsdell, of this city, who first pointed 
out to me that Scarboro’ sand contains particles which a 
magnet can extract. In winter when the sand is damp it will 
cling to anything, so the experiment is best tried with sand 
which has been washed free from salt and then dried. If a 
powerful magnet is trailed through this it will come out 
bristling with black particles. Under the microscope these 
appear rounded, glossy-black and highly polished. In seeking 
for their origin we have examined the purple-red sand of 
Cornelian Bay, because its colour suggests iron ; and here we 
find the crop of attractable particles unusually rich. In fact, 
time after time, a magnet can be passed through a handful of 
sand, and will go on bringing out particles, so that even at the 
end of an hour, when a yield of 2 or 3 per cent, has been 
obtained, the supply does not seem exhausted. It would seem 
however, that the particles are not all equally attractable. 
On examining the density of this red sand, it is found to be 
about 31 times as heavy as water ; whilst the yellow sand of 
the South Bay is only about 2J times (more exactly 2*63) as 
heaVy as water. 
Moreover if some red sand which has been nearly cleared of 
its magnetic particles is heated to redness, it will again yield 
a luxuriant crop. Indeed on very strongly heating it almost 
all becomes attractable. A smell of burning sulphur during 
the process suggests that we may be dealing among other 
things with a sulphide of iron. The particles extracted after 
heating are not so brilliantly black as those first obtained. 
We have not found out for certain the exact composition of 
either the shining black or the duller particles. They can 
hardly be metallic iron which would rapidly rust on alternate 
exposure to air and sea water. Mr. Platnauer has found that 
the portion extracted by a magnet consists of Magnetite 
with some Haematite, a little Chromite. and Pvrrhotine 
(magnetic pyrites). He also points out that Haematite is only 
