116 



AGRICULTURAL CHEMISTRY. 



death by inflicting an injury on particular | During the passage of these salts through 

 organs, either when heated to redness, or the lungs, their acids take part in the pecn- 



when in the form of a sharp knife. Such 

 substances are not poisons in the limited 

 sense of the word, for their injurious action 

 depends merely upon their condition. 



The action of the proper inorganic poisons 

 is owing, in most cases, to the formation of 

 a chemical compound by the union of the 

 poison with the constituents of the organ 

 upon which it acts; it is owing to an exer- 

 cise of a chemical affinity more powerful 

 lhan the vitality of the organ. 



It is well to consider the action of inor- 

 ganic substances in general, in order to ob- 

 tain a clear conception of the mode of action 

 of those which are poisonous. We find 

 that certain soluble compounds, when pre- 

 sented to different parts of the body, are ab- 

 sorbed by the blood, whence they are again 

 eliminated by the organs of secretion, either 

 in a changed or in an unchanged state. 



Iodide of potassium, sulpho-cyanuret of 

 potassium, ferro-cyanuret of potassium, 

 chlorate of potash, silicate of potash, and all 

 salts with alkaline bases, when administered 

 internally to man and animals in dilute solu- 

 tions, or applied externally, may be again 

 detected in the blood, sweat, chyle, gall, and 

 splenic veins ; but all of them are finally ex- 

 creted from the body through the urinary 

 passages. 



Each of these substances, in its transit, 

 produces a peculiar disturbance in the or- 

 ganism in other words, they exercise a 

 medicinal action upon it, but they them- 

 selves suffer no decomposition. If any of 

 these substances enter into combination with 

 any part of the body, the union cannot be 

 of a permanent kind; for their reappearance 

 in the urine shows that any compounds 

 thus formed must have been again decom- 

 posed by the vital processes. 



Neutral citrates, acetates, and tartrates of 

 the alkalies, suffer change in their passage 

 through the organism. Their bases can 

 indeed be detected in the urine, but the acids 

 have entirely disappeared, and are replaced 

 by carbonic acid which has united with the 

 bases. (Gilbert Blane and Wohler.) 



The conversion of these salts of organic 

 acids into carbonates, indicates that a con- 

 siderable qantity of oxygen must have united 

 with their elements. In order to convert 1 

 equivalent of acetate of potash into the car- 

 bonate of the same base, 8 equivalents of 

 oxygen must combine with it, of which 

 either 2 or 4 equivalents (according as an 

 acid or neutral salt is produced) remain in 

 combination with the alkali; whilst the re- 

 maining 6 or 4 equivalents are disengaged 

 as free carbonic acid. There is no evidence 

 presented by the organism itself, to which 

 these salts have been administered, that any 

 of its proper constituents have yielded so 

 great a quantity of oxygen as is necessary 

 for their conversion into carbonates. Their 

 oxidation can, therefore, only be ascribed 

 to the oxygen of the air. 



liar process of eremacausis which proceeds 

 in that organ ; a certain quantity of the oxy- 

 gen gas inspired unites with their constitu- 

 ents, and converts their hydrogen into water, 

 and their carbon into carbonic acid. Part 

 of this latter product (1 or 2 equivalents) 

 remains in combination with the alkaline 

 base, forming a salt which suffers no farther 

 change by the process of oxidation ; and it 

 is this salt which is separated by the kidneys 

 or liver. 



It is manifest that the presence of these 

 organic salts in the blood must produce a 

 change in the process of respiration. A part 

 of the oxygen inspired, which usually com- 

 bines with the constituents of the blood, 

 must, when they are present, combine with 

 their acids, and thus be prevented from per- 

 forming its usual office. The immediate 

 consequence of this must be the formation 

 of arterial blood in less quantity, or in other 

 words, the process of respiration must be 

 retarded. 



Neutral acetates, tartrates, and citrates 

 placed in contact with the air, and at the 

 same time with animal or vegetable bodies 

 in a state of eremacausis, produce exactly 

 the same effects as we have described them 

 to produce in the lungs., They participate 

 in the process of decay, and are converted 

 into carbonates just as in the living body. 

 If impure solutions of these salts in water 

 are left exposed to the air for any length of 

 time, their acids are gradually decomposed," 

 and at length entirely disappear. 



Free mineral acids, or organic acids which 

 are not volatile, and salts of mineral acids 

 with alkaline bases, completely arrest decay 

 when added to decaying matter in sufficient 

 quantity ; and when their quantity is small, 

 the process of decay is protracted and re- 

 tarded. They produce in living bodies the 

 same phenomena as the neutral organic 



salts, but their action depends upon a differ- 

 ent cause. 



The absorption by the blood of a quantity 

 of an inorganic salt sufficient to arrest the 

 process of eremacausis in the lungs, is pre- 

 vented by a very remarkable property of all 

 animal membranes, skin, cellular tissue, 

 muscular fibre, &c. ; namely, by their inca- 

 pability of being permeated by concentrated 

 saline solutions. It is only when these so- 

 lutions are diluted to a certain degree with 

 water that they are absorbed by animal 

 tissues. 



A dry bladder remains more or less dry 

 in saturated solutions of common salt, nitre, 

 ferro-cyanuret of potassium, sulpho-cyanu- 

 ret of potassium, sulphate of magnesia, 

 chloride of potassium, and sulphate of soda. 

 These solutions run off its surface in the 

 same manner as water runs from a plate of 

 glass besmeared with tallow. 



Fresh flesh, over which salt has been 

 strewed, is found after 24 hours' swimming 

 in brine, although not a drop of water has 



