94
ELEMENTS OF MATERIA MEDICA.
stances thus denominated are most inconstant in their effects; somuch so, indeed, that some persons have doubted whether there areany agents which ought to be so designated.
The quantity of urine secreted in the healthy state is liable to consi-derable variation. Temperature, season of the year, climate, and time ofday, are among the common circumstances modifying this secretion.Whenever an unusual quantity of aqueous fluid is taken into the system,the kidneys are the organs by means of which the excess is got rid of.If the customary discharge from the skin or lungs be checked, by cold,for instance, the kidneys endeavour to make up for the deficiency ofaction in the other organs. Again, if transpiration be promoted, as byexternal warmth, the secretion of urine is diminished. Hence when wewish to augment the renal secretion, diluents should be freely adminis-tered, and the skin kept cool.
Mr. William Alexander (Experimental Essays, Edinburgh , 1768)endeavoured to determine, as nearly as possible, the relative powers ofdifferent diuretics, and he has given the following tabular views of hisresults:—
A Table of the different quantities of urine always discharged in an equal time; viz.from nine o’clock in the morning till two o’clock in the afternoon, when an equalquantity of the same liquid was drunk, but with different diuretics, in differentquantities, dissolved in it.
s
5
9
By lbj. 3 vijss
simple infusion of bohea tea, standard,
15
4
0
By do.
with 3 ij. of salt of tartar -
22
7
2
By do.
• • 3 ij. of nitre -
22
0
0
By do.
• • 4 drops oil of juniper -
30
3
0
By do.
•• 3j. salt of wormwood
19
7
>i
By do.
• • 3ij. Castile soap -
19
1
l
By do.
• • a teaspoonful of apt. nitr. dulc. •
17
6
11
By do.
• • 15 drops of tinet. cantharides
1(1
4
0
Bv do.
•• 5ij. of sal. polyehrest -
1(1
3
0
Bv do.
• • 5ss. of uva ursi -
16
1
01
Bv do.
• • 5.j- °f magnesia alba ...
15
5
0
By do.
♦ • 5ij. of cream of tartar
10
2
01
A Table of the different quantities of urine evacuated in the same space of time, afterdrinking the same quantity of different liquors.
By lbj. ^vijss. of
weak punch, with acid •
5
- 21
5
2
9
3
Bv
do.
new cow whey ...
- 18
6
0
Bv
do.
decoct, diuret. Pharm. Edin. -
- 17
5
0
By
do.
London porter ...
- 16
7
0
By
do.
decoct, bardan. Pharm. Edin.
- 14
7
0
Bv
do.
warm water gruel -
- 14
6
2
B'v
do.
small beer -
- 13
7
1
Bv
do.
warm new milk -
- 11
7
0
These tables are to a certain extent useful, but as diuretics act veryunequally at different times, and cannot, therefore, be relied on, thevalue of Mr. Alexander’s experiments is considerably diminished.
At pages 14 and 15 of this volume I have given a list of the substanceswhich pass off by the urine. Many of these, especially the salts, stimu-late the kidneys:—they do this probably by a local action in theirpassage through the renal vessels. Several of the vegetable diureticsowe their activity to volatile oil: such are, copaiva, the turpentines,juniper, and oil of eajuput. The oil probably acts on the kidneys bylocal contact, after its absorption. The modus operandi of squills andcolchicum may, perhaps, be similar : that is, their active principles may