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working of his own inventions. 
Fan. 16, 1873] 
MINERAL PHOSPHATES 
Mineral Phosphates and Pure Fertilisers. By Campbell 
Morfit, M.D., F.C.S. (London: Triibner and Co.) 
eo date of the patent taken out by Mr. Lawes, 
in 1842, for treating mineral phosphates with sul- 
phuric acid, has proved the date of the commence- 
ment of a new industry which has now attained to 
vast proportions. At present the manufacture of super- 
phosphates in Great Britain can hardly be short of 
400,000 tons per annum, and the market value of the 
same cannot be under 2,400,000/. Competition natu- 
rally tends to develop improvements, and of late years 
several novel processes have been suggested for the better 
treatment of mineral phosphates. Dr. Morfit’s book is 
mainly devoted to a description of these new methods, 
and more especially to a detailed account of the practical 
The object of all these 
processes is the preparation of “ Pure Fertilisers.” The 
mineral phosphates at the disposal of the manufacturer 
contain 50-80 per cent. of tricalcic phosphate, the poorer 
minerals preponderating. In making ordinary super- 
phosphate the whole mineral is treated with sulphuric 
acid, and the resulting superphosphate is of course rich 
or poor according to the quality of the mineral taken. 
But in making a “ Pure Fertiliser” the aim is to separate 
the calcium phosphate from the original mineral and 
offer it for sale in a nearly pure state. The production 
of a pure phosphate is of course a more costly operation 
than the simple treatment of the powdered mineral with 
sulphuric acid, and we believe that these pure fertilisers 
will consequently not be able to compete with ordinary 
superphosphate, except in cases where, as in America, 
the manure has to be transported over great distances, 
and small bulk is therefore a desideratum. Their advan- 
tage over the comparatively poor superphosphate is much 
lessened by the fact, that the non-phosphatic matter in 
superphosphate is principally gypsum, which is itself a 
valuable manure. There is one class of mineral phos- 
phates, however, which is wholly unsuited for the manu- 
facture of superphosphate—we allude to the native phos- 
phates of aluminium ; the processes patented by Mr. P. 
Spence and Mr. J. Townsend for the extraction of the 
phosphoric acid are in this case most valuable. 
Dr. Morfit’s plan is to roast the powdered crude cal- 
cium phosphate, then dissolve it in strong hydrochloric 
acid, and precipitate the solution by ammonia gas, by 
lime, by whiting, or by the addition of a previously pre- 
cipitated mixture of the oxides and phosphates of iron 
and aluminium. When the solution is left acid by an 
insufficient use of lime, or when the last two precipitants 
are employed, the precipitate obtained consists chiefly of 
dicalcic phosphate, The resulting calcium phosphate is 
either sold as such, or else converted into a superphosphate. 
The acid mother liquors are precipitated with lime, which 
throws down the iron, aluminium, and remaining phos- 
phoric acid ; the purified calcium chloride is then boiled 
down and brought into a solid state for sale. There is 
thus a constant production of two bye-products. The 
author regards them as valuable materials ; the calcium 
chloride is to be used for making Ransome’s artificial 
stone, and the ferruginous phosphates for the clarification 
of sewage. This scheme looks promising on paper, but 
NATURE 
199 
must require special local circumstances for its fulfil- 
ment. 
The reader will find in this book a full account of the 
patents of Way, Spence, Townsend and others, who have 
worked on the subject, together with much practical in- 
formation as to the construction of apparatus and the 
performance of manufacturing operations ; the subject 
is, in short, fully treated. The book contains, however, 
some very unpractical schemes, as when the author 
proposes the universal adoption of earth closets, with the 
recovery of the nitrogen by combustion with soda-lime, 
and the production of phosphoric acid by lixiviation of 
the residue. Nowas fully saturated closet earth contains, 
according to Voelcker, but ‘33 per cent. of nitrogen, and 
*55 per cent. of phosphoric acid more than the loam 
originally taken, the notion seems to us somewhat im- 
practicable. The book also contains, we are sorry to 
say, examples of doubtful chemistry. 
We refer in conclusion to some statements which we 
consider to be errors in the volume. 
Dr. Morfit gives proportions for the preparation of 
manures for allthe ordinary crops ; these proportions are 
professedly based on the composition of the crops them- 
selves. All these mixtures contain large amounts of 
potash, and the manures for wheat, clover, and turnips 
all contain the same amount ef nitrogen. Having said 
this, we have made it plain to every scientific agriculturist 
that the author’s notions are quite unpractical ; he has, in 
fact, fallen into the common mistake of chemists who know 
little of agriculture. If manures are to be constructed 
onthe basis of returning to the land what has been taken 
from it, we have'then to look at the composition of the 
materials sold off the farm, and not at the composition of 
the crops grown, as these are in great part consumed on 
the farm itself. But even this is not the practical aspect 
of the case. Each crop has, in fact, a characteristic 
capacity for self-supply ; it obtains with ease some por- 
tions of its food, and others with difficulty ; the aim of 
economic manuring should therefore be to supplement 
the plant’s weakness. Thus, wheat supplies itself with 
difficulty with nitrogen, while clover has a wonderful 
power of self-supply in this particular. The scientific 
farmer therefore manures wheat liberally with nitrogen, 
and gives little or none to clover. The mere chemist 
would do just the reverse, as clover contains much more 
nitrogen than wheat. Manuring, on the principles of the 
author, is simply impossible ; the manures would often 
cost more than the increase of crop obtained. 
Dr. Morfit again finds fault with the ordirtary commer- 
cial analyses of phosphatic materials, and devotes a whole 
chapter to directions for the analysis of mineral and other 
phosphates. We strongly recommend the reader not to 
follow Dr. Morfit’s guidance, It is quite impossible to 
enter here into details of the doubtful chemistry that 
occurs throughout the chapter, but we may refer to one 
point which governs many of the author’s conclusions. 
He professes to ascertain the “ individual combinations of 
the phosphoric acid present,” a task which other chemists 
would probably express their inability to do, Heaccom- 
plishes this by assuming that the phosphoric acid which 
is precipitated as ferric phosphate in his analysis, existed 
in the same state in the original mineral. By this means, 
and by assuming in the same way that other precipitates 
