ARTIFICIAL MANURES. 179 
turnip crop the most economical phosphatic manure 
was insoluble phosphate of lime from any source ground 
down to an impalpable powder.” It is only natural 
for us to expect that in Ceylon, with its command 
of bone manure and forcing climate, economy will lie 
in the direction of improved grinding, so as to get 
the natural phosphates into a state of impalpable 
powder rather than in the importation of super- 
_ phosphates. 
Referring again to Dr. Voelcker’s useful rules No. 6 
shews that he quite agrees with the lae Professor 
Anderson and all other eminent chemista, in disregard- 
ing carbonate of lime in the commercial valuation of 
compound manures, such being always expected to shew 
their value from their nitrogen and phosphates. Mr. 
Hughes seems to be of opinion that the potency of 
a tropical climate, coupled with scarcity of lme in 
the soil, justifies a more lberal treatment of this in- 
gredient. Such recognition can affect the analyst at 
least only favourably, so that it may be left an open 
question between buyer and seller in the case of © 
poudrette. Were I a buyer, however (except in the 
case of pure wood ashes which do not properly come 
under the head of compound manure), i would stick 
to the good old rule, as it keeps the manures pure 
and so prevents the artificial manure trade from be- 
- coming demoralised. 
Potash so rarely occurs in ordinary artificial manures 
in England in appreciable quantity that Dr. Voelcker 
has not taken account of it in these rules; but when- 
ever it occursin fair proportion a high value is assigned 
to it. As nitrogen assists plants to assimilate potash 
so potash assists plants to assimilate nitrogen.— 
. MicuaL CocHRAN. 
HINTS FOR THE CONSIDERATION OF COFFEE- 
PLANTERS. 
(From the Ceylon Observer, March 15th, 1880.) 
An experienced and observant visiting agent hazar- 
ded the opinion to us the other day that in many 
parts of the younger districts coffee has been planted 
too widely apart. He remarked on the smaller num- 
ber of feeding rootlets found on trees which have 
grown up in the leaf disease period than on those 
which date back previous to the appearance of this 
scourge, and intimated his belief that trees with a 
poor display of rootlets planted widely apart were un- 
able to absorb a due proportion of the moisture in 
the soil. The consequence of this was that the soil 
