340 
Ghemical Ckanfjes in the Fcrmeniatioii of Duiiy. 
We have a further confirmation of this view in tiie fact that 
phosphuretted hydrogen is actually generated in the human body 
Irom the phosphorus or phosphates of the food, and that the 
same change goes on in a mass of urine left to putrefy. Mr. 
Stephens (^Book of the Farm, vol. i. p. 485, ed. 2nd) has a table 
(extracted in Appendix) to show the changes which take place 
in urine when suffered to putrefy for a montli in contact with the 
air. The last line of this table is in such a form as to prevent 
calculation, and we are therefore obliged to content ourselves 
with general statements. No thoughtful person however can 
read it without inquiring what has become of the sulphuric and 
phosphoric acids expressed on one side by the figures 475 and 
human remains buried around it. But the nitrogen of these nitrates, and the 
stilphur of the sulphates, were unquestionably given ofFduring decay as compounds of 
hi/drni/c/i (viz., as ammonia and sulphuretted hydrogen); and if these suffered 
oxidation in their passage through the soil, are we not led at once to infer the 
same of phosphorus ? If this be so, we are following an evident direction of 
nature, when we mix earth with manure, to arrest these volatile compounds in the 
first instance, till we can bury them in our fields, to be fully prepared for the use 
of vegetation. 
The follovv'ing extracts appear illustrative of what is advanced above : — 
" The common potato, in a state of putrefaction, is said to give out a most vivid 
light, sufficient to read by. This was particularly remarked by an officer on guard 
at Strasliurg, who thought the barracks were on fire in consequence of the light 
thus emitted from a cellar full of potatoes." — Lindley, Vegetable Kingdom, 
p. 021. 
The mean of Fromberg's analysis of potato-ash is (Stephens, vol. i. p. 27.5) : — ■ 
Potash .'iS-TS 
Soda 1-8G 
Lime 2-07 
Magnesia ."j-aS 
Oxide of iron and alumina O'.'j'i 
Phosphoric acid 12'57 
Sulphuric acid 1.3"f)5 
Chlorine 4-25 
Silica 4-23 
100-18 
The explanation of this phenomenon appears to be that the heat of decomposi- 
tion, confined in the close cellar, rose sufficiently high to inflame the phosphuretted 
hydrogen given off during its generation. The large percentage of phosphorus 
shown bv analysis will account for the abundance of the gas. 
" Dr. "Hulme (Phil. Trans, for 1790) establishes that the quantity of light 
emitted by dead animal substances is not in proportion to the state of putrefaction 
in them, as is commonly supposed ; but on the contrary the greater the putres- 
cence the less light is evolved. It would seem that this element, endowed with 
preeminent elasticity, is the first to escape from the condensed state of combination 
in which it had been imprisoned by the powers of life ; and is followed, after some 
time, by the relatively less elastic gases whose evolution constitutes putrefaction." 
— Ure, Dictionary of Chemistry, art. " Light," p. 584. Edition 4th. 
The reader who bears in mind the quantity of phosphorus contained in animal 
substances and the insolubility of its compound with hydrogen in the water of 
decomposition, will be able to explain the fact far more accurately than by the 
imprisonment of light by vital power. 
