294 POISONS : THEIR EFFECTS AND DETECTION. [§ 358 . 
half a grain a very full dose, and, in cases requiring it, would seldom 
prescribe at first more than to J grain. 
The dose of solid opium for a horse is from 1-77 grin, to 7-08 grms. 
(f drachm to 2 drachms) ; in extreme cases, however, 4 drachms (14*16 
grms.) have been given. 
The dose for large cattle is from *648 grm. to 3*88 grms. (10 to 60 
grains) ; for calves, *648 grm. (10 grains) ; for dogs it is greatly regulated 
by the size of the animal, 16*2 to 129*6 mgrms. (J grain to 2 grains). 
Fatal Dose. —Cases are recorded of infants dying from extremely 
small doses of opium, e.g . *7, 4*3, and 8*1 mgrms. (y^, and J of a 
grain) ; but in such instances one cannot help suspecting some mistake. 
It may, however, be freely conceded that a very small quantity might 
be fatal to infants, and that 3 mgrms. given to a child under 1 year 
would probably develop serious symptoms. 
The smallest dose of solid opium known to have proved fatal to 
adults was equal to 259 mgrms. (4 grains) of crude opium (Taylor), 
and the smallest dose of the tincture (laudanum), 7*0 c.c. (2 drachms) 
( Taylor) ; the latter is, however, as already shown, uncertain in its 
composition. 
A dangerous dose (save under special circumstances) is :—For a 
horse, 14*17 grms. (4 drachms) ; for cattle, 7*04 grms. (2 drachms) ; for 
a dog of the size and strength of a foxhound, 204 mgrms. (3 grains). 
Enormous and otherwise fatal doses may be taken under certain con¬ 
ditions by persons who are not opium-eaters. The senior author has 
seen 13 cgrms. (2 grains) of morphine acetate injected hypodermically 
in a strong man suffering from rabies with but little effect. Tetanus, 
strychnine, convulsions, and excessive pain all decrease the sensibility 
of the nervous system to opium. 
§ 358. General Method for the Detection of Opium. —It is usually 
laid down in forensic works that, where poisoning by opium is suspected, 
it is sufficient to detect the presence of meconic acid in order to establish 
that of opium. In a case of adult poisoning there is generally substance 
enough available to obtain one or more alkaloids, and the presence of 
opium may, without a reasonable doubt, be proved, if meconic acid (as 
well as either morphine, narcotine, thebaine, or other opium alkaloid) 
has been detected. Pills containing either solid opium or the tincture 
usually betray the presence of the drug by the odour, and in such a case 
there can be no possible difficulty in isolating morphine and meconic 
acid, with probably one or two other alkaloids. The method of extrac¬ 
tion from organic fluids is the same as before described, but it may, of 
course, be modified for any special purpose. If opium, or a preparation 
of opium, be submitted to Dragendorff’s process (see p. 256), the follow¬ 
ing is a sketch of the chief points to be noticed. 
If the solution is acid — 
