In the tissues of the body there are continual changes going on, termed
in technical language tissue metamorphosis; the waste products that are
thus formed constitute a group of highly nitrogenized substances, which
in a healthy condition of the system are eliminated by the kidneys.
These nitrogenized products are urea, urate of soda and uric acid;
the accumulation of any of these substances in the blood gives rise
to disease; the former is the cause of uræmia and uræmic convulsions,
and the latter have been detected in the blood and exudations in cases
of gouty and rheumatic disease. The characteristic gouty deposit is
urate of soda, due to an excess of nitrogenous elements of the blood.
An excess of uric acid constitutes a disease which is first recognized
by a reddish crystalline sediment in the urine; the term _lithiasis_
has been employed to denote this peculiarity. These lithates are always
to be found in the urine of high livers and are due to an excessive
consumption of nitrogenous food. The great English authority, Dr.
Murchison, looks upon the excessive production of uric acid, or lithic
acid, as it is sometimes called, as due to one of two causes and
sometimes to both, namely to the excessive consumption of nitrogenous
food, or to an inability of the liver to perform its duty, which among
other things is to dispose of the nitrogenous waste products. From
this point of view lithates or brick dust deposits in the urine are
no sign that the kidneys are deranged, but quite the reverse may be
true when the kidneys are overburdened in eliminating this excessive
waste, for they are performing extra duty, which excess in living or a
sluggish liver imposes upon them, and this may excite inflammation in
the tissues of the kidneys and develop into what is known as Bright’s
disease.
This very interesting exposition of the deposit of lithates or gravel
in the urine will naturally suggest that when the urine is overloaded
with these nitrogenous products nitrogenous food like eggs, cheese,
beef, etc., should not be eaten for awhile, and that a vegetable diet
should be principally relied upon, thus giving the liver a vacation;
the diet should be supplemented with plenty of clean fresh water, and
no liquors of any sort should be taken by those whose liver is affected.
Starch, sugar and fat are composed of carbon, hydrogen and oxygen;
starches and sugars are termed carbo-hydrates; because the hydrogen
and oxygen is always present in them in equal atomic weights so as to
represent water; while in the fats the oxygen is considerably less.
This is exemplified by comparing the chemical equivalents of starch and
cane sugar with those of fats:
Starch C_{12}H_{10}O_{10} Oleine C_{94}H_{87}O_{15}
Cane sugar C_{12}H_{11}O_{11} Margarine C_{76}H_{75}O_{12}