ON THE CULTIVATION OF INDIGENOUS OPIUM. 327 
sun. In the latter climates in particular the seed must be sown in 
autumn. 
M. Aubergier thinks that land reposing on volcanic formations is 
very favourable to the culture of poppies ; and it is to this kind of soil 
that he attributes, in a great degree, the success of his culture in 
Auvergne. 
4. Analysis of Soils. 
The analysis of soils, as its name indicates, is an operation the object 
of which is to determine the nature and proportion of the different 
substances that compose a given soil, so that the agriculturist may 
arrange it in one of the preceding classes. 
To make this analysis we purpose following the simple and easy 
process pointed out by Professor Lassaigne of the Imperial School at 
Alfort. 
First find the proportion of moisture contained in the earth. Then 
separate the matters soluble in water from those not so, and finally 
determine, successively, the nature of the bodies which compose the 
watery solution, and the residue. 
The proportion of humidity may be estimated by drying a given 
weight of earth for analysation, and taking care not to decompose the 
organic substances found in it. 
After this determination, separate the gravel and stones, weigh them 
and ascertain their nature by means of hydrocloric or nitric acid ; they 
will be dissolved by effervescence if they are formed of chalk (carbonate 
of lime), but will remain insoluble if silica forms the base. 
Soils, besides the gravel and stones which mix with them in variable 
quantities, contain a greater or less proportion of fine sand, which can 
be separated by stirring the earth in water. 
The sand, being heavier, is precipitated in less than a minute ; it is 
then collected in a vase by decanting, and when dry is to be weighed, 
its nature is as easily known by an acid as that of the gravel. 
The finer parts of earth, and the animal and vegetable matter, less 
heavy than the sand, remain for a longer time suspended in the water. 
The liquid is to be filtered through paper to separate them. 
As the water which served for this operation contains the saline and 
soluble organic matters, if any existed, in the earth, it is to be evaporated 
to dryness in a crucible or small saucer of clay for roasting samples of 
ore, so as to weigh the residue and examine it separately. 
The disunited matter of the soil, separated by filtration is the most 
important to determine ; it contains generally the remains of organic 
matter, of silica, of alumina, bi-oxide of iron, carbonate of lime, and 
sometimes carbonate of magnesia. 
A portion is to be calcined in a crucible to a red heat, to ascertain 
the weight of the organic matter by the loss of weight sustained. But 
as this part of the loss is due also to the carbonic acid, which proceeds 
