720 
Supplement to the " Tropiml Agrkultumt." 
[April 2, 190G, 
it will be found that in the humid regious of the 
United State- the percentage of soluble matter 
depends upon the size of the soil grain.«. The soils 
of the humid regions vary much in size of grain 
and extent of surface exposed on these grains upon 
which the water may act. The following table 
shows tlie relation in a general way between tlie 
texture of the soil and the percentiige of soluble 
matter present. — 
Melation between texture of soils and. percentage 
of salt. 
Kind of soil. 
Local!ity. 
« o o 
MS?.*" 
IP 
Florida soils ... — ... 1 1 
Truck — ... 5 10 
Limestone soils... Maryland .,,18 G 
Do ... Pennsylvania... .3.3 27 
Do ... Kentucky ... 55 17 
Do ... Virginia ... 56 78 
It will be seen from the table that the soil which 
had the greatest extent of surface for the water to 
act on (or, in other words, the soil which was 
made up of the finest grains) had also the greatest 
percentage of salt which was soluble. It is a 
well-known fact, also, that the general agricultural 
value of a soil varies in nearly this same ratio, that 
isvto say, a heavy soil is better for general farming 
purposes than a light, sandy soil. 
There is another point of difference between the 
humid and arid soils which is of general interest 
as well as of general importance. The soils of the 
humid regions contain much more soluble matter 
than the subsoils, that is to say, the greater part 
of the soluble matter is concentrated within the 
surface foot of the soil. About 60 per cent of the 
rainfall of the humid regions either washes over 
the surface of the ground or else washes through 
the soils and skins down below the subsoil to 
appear at a lower level and be carried off by 
streams into the ocenn. This has been going on 
for ages, and the amount of soluble matter left is 
very small, only sufficient to supply the plant 
roots. 
The absorbing action of the soil grains retains 
the greater part of the suit as it becomes soluble 
within the .surface foot of the soil, and it is here 
used by the plants. Below this, in the subsoil, in 
the region where the action of weathering is re- 
duced to a minimum, the amount of soluble matter 
found is very small. 
In the arid regions, where the rainfall is not 
sufficient to keep the soil continuously moistened 
to any great dej)th, and where the air is drier and 
evaporation much more rapid, the proportion of 
the rainfall drained from the land by the rivers is 
much less, in some ciises less than 10 per cent, and 
in nearly all ciises of We.stern risers less than 25 
per cent. Thus, with a small rninfall, very little 
water leaches through the soil, nnd therefore very 
little soluble matter is washed out. 
In fact, in most of our arid pridries the soil is 
never wet from the surface to a depth of more 
than 5 or 6 feet. When the raii:fall soaks down 
to the subsoil it cariies with it some of the soluble 
matter which is in the soil. This soluble matter 
xi absorbed by and condensed upon the grains of 
the subsoil, and when the water is again brought 
to the surface of the ground by the evaporation of 
the soil water, part of the soluble matter remains 
in the lower layers of the soil. Then, if an ex- 
amination is made of the prairie soils as they 
normally occur, more soluble matter will be found 
in the subsoil than in the soil, while in the humid 
regions the conditions are just the reverse. 
BOEACIC ACID AS A FOOD PRESER- 
VATIVE. 
Boracic or boric acid and its sodium salt 
Borax are now extensively used for the pre- 
servation of liquid and solid foods such as milk, 
butter, cream, fish and meat that a short account 
of them should prove of general interest. We 
are indebted for our facts to an instructive paper 
on this subject by I'rof. Briinnich, F,C.s, 
In all preservatives sold, boric acid and borax 
are the chief ingredients. Annlyses of some of 
these preparations are given below : — 
Preservitas contained : 
Water ... 34*50 percent. 
Soda ... .5-58 „ 
Boric acid ... 47'39 „ 
Salt ... 9-33 „ 
Saltpetre ... 3-00 „ 
99-80 
Sal praeservare contained : 
Water ... 34-30 
Soda ... 4-96 
Boric acid ... 51-80 
Salt ... 8-52 
per cent. 
Preservative contained : 
Water 
Boric acid 
Salt 
Saltpetre 
Preservative contained 
Water 
Boric acid 
Soda 
99-58 
87-70 
40 60 
20-16 
3- 03 
101-49 
39-30 
57-26 
4- 35 
100-91 
per cent. 
per cent. 
The effect of boric acid and borates on man and 
animals has been studied by a great number of 
scientists, but the results of their investigators 
are by no means conclusive. Some of the in- 
vestigators — for instance, the French Commission 
appointed to study the influence of boracic acid 
on the human system — found that it could be 
taken for a considerable time without injurious 
effects. More recent experiments proved that 
small doses of boric acid, or borax, have no in- 
juiious effects, whereas larger doses produce 
distinct physiological disturbances— a danger will 
c insequently arise if boric acid is used indiscri- 
minately as a preservative. Th« Medical OfiSceE. 
for Health for East Kent, Dr. M, E. Robinson, ha» 
