PRESIDKXT’s ADI)REb.“ 
11 
al)lo to animal life, and counteracting the putrefactive decomposition 
80 soon set up by minute Fungi in the absence of oxygen. 
This short resume of the present state of our knowledge on tlie 
subject of micro-organisms is, however, only preliminary to one 
particular section of natural history which I desire to discuss more 
fully, that is to say, the Process of Nitrilication which occurs in 
Soils. From very remote times wo know of the existence and use 
of Nitrate of Potash, commonly called nitre, ;is being collected 
from the soil in hot climates, especially India and China. It is, as 
we all know, one of the chief ingredients in the manufacture of 
gunpowder; and whatever may have been the date of the discovery 
of this explosive in Europe, similar compositions were certainly 
known and used from a very early date by the Chinese, lly far 
the largest fiart of the raw nitre now used in Europe for 
guu|)owder, and other manufacturing purposes, comes still from 
the East Indies ; and it may bo interesting to mention how the 
]U’oduction of it is managed, as described by Dr. Palmer of the 
liongal Army. There is a caste of men known as Sorawallalis 
{sora meaning nitre), who make it their business to collect the 
raw material, manufacture the salt, and sell it either for freezing 
mixtures or for exportation. This Sorawallah goes about villages 
examining the small surface-drains, which issue from holes in the 
mud wall usually found around native dwellings and their cow 
houses. When ho detects a faint wliite veil-like patch of crystals 
on the borders of these drains, ho knows that a considerable 
quantity of this nitre exists on or near the surface of all the 
surrounding earth, and ho therefore collects by scraping, a thin 
coating of this earth, and extracts the nitre by lixiviating it with 
water, and afterwards purifying the resulting salt by crystallization- 
The collector takes fresh portions from the same spots of ground 
from week to week, year to year, and from generation to generation, 
according to the manner of the Eastern world. The production of 
nitrt' is conshrnt, so long as the place continues to be inhabited. 
It even continues to appear in large, but gradually decreasing, 
quantities, for years after the village is deserted. 
