15§ 
THli; T^ROPICAL AGRlCULTTTrJST. [Sept. 2, 1901. 
one would think it would be wiser to suspend jiiclg- 
ment until Hxpej'imt-;ut<il evidence was forthcouiing. 
By Mr, Hughes' sugg-isfcion it seemed that a fac- 
tor which ix'udered upi-'iphosphates unsuitable for 
certain soils was r.jiuo"e i in a vecy simple manuer, 
and at the sam-s timt yi.-Med a mix'ui'e in a con- 
venient from for use on the farm, which, more- 
over, 00 the face of it, mif;ht prove of high manuiial 
valne; but, of courso, this point could only be 
decided by trustworthy experimen ts, to which the 
speaker, amongst others, vould Inok forward with 
interest. A% chemists, of course, they must all admit 
that in these mixtures they had sulphuric acid, 
phosphoric acid and lime, and these bodies had 
always bien the constituents of such artificial manures 
from the bei^inning. When Mr. Hughes told him 
of his invention, it struck him that the proposal 
was somewhat retrogressive, and he suggested thut 
to him ; and further, that on putting lime into tlie 
manure the phosphoric acid would possibly assume 
a reverted condition, that was, go back to tribsaic 
phosphate. However, in practice things did not 
always happen as we expected them to happen, and 
so perhaps in this case the expected mi^ht not 
happen. He would like to ask Mr. Hughes how 
long the mixture given on the table had been 
prepared, so aa to yield G6-& of soluble matter, 
inasmuch as if it consisted of phosphate, it would 
at once put out of court Dr. Dyer's argument, as 
there was no dibasio phosphate that would give that 
soinbility in water. 
Mr. Hughes : Table III. represents the portion 
soluble in water. The whole of the phosphates 
were rendered insoluble in water, and theiefore it 
did not appear on the table. 
Mr. Louis, continuing, said, if that were the case, 
Dr. Dyer's contention niight be right Then there 
was the other point mentioned by Mr. Lloyd, and 
admitted by all who knew, that without any doubt 
it was valuable to add lime in so'ne soils ; and, as 
Dr. Voelcker held, the farmer might be free to 
buy the lime and phosphate separately and mix 
them himself ; but the farmer would not do that ; 
he liked things made easy for him, and liked to 
buy his materials ready for use as " wheat manure, " 
"barley manure," and so forth. The farmer, for 
want of means, would not put lime on his soil, but 
he knew that he must put some phosphate; and 
if he could conveniently buy the lime at a moderate 
price along with the phosphate, he would very 
likely do so, especially if he got it in a form con- 
venient for handling, and could by one sowing and 
one expenditure introduce two valuable factors into 
his soil. He was sorry to learn from the author 
that the 6o'8 was not the material one would have 
liked to see soluble and suitable for plant food, 
though it might prove suitable for Mr. Lloyd's bac- 
teria, a d probably do good in that way. 
Note. — At the time of speaking Mr. Louis was not 
aware of the fact that excess of lime was employed 
ip Mr. Hughes' mixture. 
The Chairman had no wish to stand as umpire 
between two contending parties. No doubt each of 
these materials had its value in the right place, 
and each of them was useless in the wrong place. 
If Mr. Hughes's mixture could be made at such a 
price as to be as cheap as other phosphates, he 
thought it had a considerable future before it. But 
when he considered th^t first in the making of the 
superphosphate the original raw phosphate sot diluted 
by sulphuric acid, and then still farther diluted by 
the addition of lime, the net result was a mixture 
contiining only a fraction of the tribasic calcium 
phosphate present in the raw material ; and it was 
difficult to see how such a mixture could compete 
with a niilerial like Thomas slag, which bad not 
to undergo these processes of dilution. Assuming 
that the material of Mr. Hughes was more soluble 
and more available than soluble Thomas meal, the 
question was, how could such a material, which had 
to stand the ooat of grinding, treatment with solpha- 
ric acid, lime, and carriage ou a redoced percentage of 
phosphoric acid, hope to compete with basic slag ? 
If, however, Mr, Hughes could give satisfactory as- 
surances on that point he had rendered a service 
to agriculture. 
Mr. Kdpfle said that Dr. Voelcker had referred to the 
precipat -d phosphate made on the Rhine, and had ques- 
tioned whether Air. Hughes' material would be able to 
compete with it. Was that precipated phosphate hv- 
drated He believed it was a very rich tricalcic phos- 
phate, but not hydrated. Mr. Hughes' proposal really 
was to take the hydrated P2 in the superphosphate; 
to that he added hydrated lime, and thus got a hydrated 
'^ompmad of phosphoric acid and lime. Would not 
that hydration give it such a start of superiority 
that It would answer where the precipated phosphate 
would n'-t L L I r 
The CHAtnjiAN : Does Mr. lluftle assume that a 
ditfrfrent compound would be obtained by adding 
Calcium hydroxide instead of calcium oxide ? Is there 
any chemical evidence to that eff iot ? No matter 
what form the lime may be in, the same product would 
probably result. 
Mr. IluFiLE said he thought one would get Mr. 
u '!f .:f '^o'l^POund by putting 15 to 20 per cent, of 
hyd-ated jim-^. One would want more than that to 
form a tricalcic phosphate ; but by adding 17 per 
cent, one got a phosphate which had some water and 
1°"}^ '"^e. In fact, Hughes produces an alkaline 
hydrated dicalciam phosphate in the superphosphate 
(P20.^. 0,0, CO, H„0, 2^Jus a slight excess of 
Ca02H.^0 for alkalinity. 
Mr. Stewart remarked that if one added calcium 
oxide there was a danger of forming pyrophosphate 
of lime. Did Mr. Hughes confine himself to producing 
dibasic phosphate ? Was there just sufficient lime 
to form two of CaO to one of PO 5? 
Mr. Hughes, in reply, said he was pleased to find 
that he had very little to answer. Dr. Voelcker 
had suggested that farmers would add lime to super- 
phosphate themselves. They were quite welcome to 
do so, for it would increase the sale of superphos- 
phate ; but they would find a difficulty in preparing 
a perfectly uniform mixture. Further, it was a fact 
that in those parts of the country where lime did 
not occur in sufficient quantity in the soil, the 
farmer would have to purchase it from a distance and 
at considerable cost ; therefore the appUcation of 
lime where it was most required was generally 
neglected. Moreover, instead of purchasing superphos- 
phate and lime separately, the farmer could purchase 
basic super, and so supply both available phosphates 
and lime at one dressing. With regard to preci- 
pitated phosphate, whicli had been referred to, it was 
well known that it was an expensive material, pre- 
pared by a wet process, whereas basic super was a 
comparatively cheap material prepared as a dn/ 
mixing, so that any manufacturer could make it ; 
consequently there was no fear of competition with 
precipated phosphate. Bearing in mind the opposi- 
tion that basic slag had originally met with at the 
hau ls of scietific men, and knowing the immense 
quantities of it that were now used, he took en- 
couragement that, even if his material met with 
similar opposition now, he fell confident that the 
practical results in the field would be satisfactory. 
Dr. Voelcker, interposing, said he thought it 
ojght in .iastice to be pointed out that basic slag 
aa it was kaown now was a very different body from 
the slag that was first introduced, and the results 
now obtained could not have been obtained by ttie 
material then conJemned and rightly condemned. 
Mr. Hughes, resuming, said that the only improve- 
ment that had taken place in the quality of slag 
was due to improved "grinding; and he would like 
to r.^fer to Table I., in which the Peace River phos- 
phate, with a grinding of 93-61 fineness," actually 
showed a greater amount of phosphate ' of .lime 
dissolved by the weak solution of citric .acid than 
was shown by the basic slag, the figures being 
Sl-Gi as against 18 99, Ue ventured to thinjs tM 
