2g2 TlMEHRi. 
lands. Not only does it contain the necessary elements of 
plant food, but it augments the fertility of clay soils by 
facilitating the solution of the alkaline silicates of which 
they partly consist. Gypsum dissolves in 400-500 parts 
of water ; and A. COSSA has shown by a series of ex- 
periments that water containing gypsum dissolves from 
two to three times as much mineral salts out of the 
rocks of which clay is formed as pure water does. The 
presence of gypsum in soil is also of benefit from its power 
of absorbing and fixing atmospheric ammonia. Insoilsdefi- 
cient in sulphuric acid the addition of gypsum in the 
proportion of from one to two tons per acre is well 
worth a trial. The substance is cheap, it can do no 
harm, and may be productive of immense benefit. I 
strongly recommend an extensive trial to be made of its 
merits.* 
The only remaining substance that it is necessary 
to notice is phosphoric acid. This is usually applied in 
one or other of the various forms of phosphate of lime ; 
and experiments are much wanted to decide whether 
insoluble phosphate in a finely divided condition is equal- 
ly efficacious as a cane fertilizer with that rendered solu- 
ble by sulphuric acid, and known as " soluble'' phos- 
phate or super-phosphate of lime. Insoluble phosphate 
* Since writing the above I have had sent to me an extract from a 
letter giving the results of trial with gypsum in a cane-field, made by 
the Hon. W. Russell at my suggestion. The extract is as follows : — 
" The Meld No. 20 P. W. to which the gypsum was applied has improved 
wonderfully, and is now about 20 per cent, better than the adjoining 
field No. 19, which was cut and planted at the same time, and at the 
start off was the better of the two. I further noticed at the small 
drain heads, where the indications of iron were most noticeable and 
where the canes appeared stunted and dry, that a marked improvement 
has taken place". 
