_Tests._--Strychnine has a characteristic, very bitter taste; it imparts this taste to even very dilute solutions; it is unaffected by sulphuric acid, but gives a purple-blue colour, changing to crimson and light red, when the edge of this solution is touched with dioxide of manganese, potassium bichromate, ferricyanide of potassium, or permanganate of potassium. This test is so delicate as to show the 1/25000 of a grain of the alkaloid. A very minute quantity (1/5000 grain) in solution placed on the skin of a frog after drying causes tetanic convulsions. =Brucine.=--This alkaloid, found associated with strychnine, possesses the same properties, though in a less powerful degree. Nitric acid gives a blood-red colour, changed to purple with protochloride of tin. XLV.--CANTHARIDES =Cantharides.=--Spanish fly, or blistering beetle, is the basis of most of the blistering preparations. It is sometimes taken as an abortifacient or given as an aphrodisiac, but whether it has any such action is open to question. It acts as an irritant to the kidneys and bladder, and sometimes produces haaematuria and a good deal of temporary discomfort. _Symptoms._--Burning sensation in the throat and stomach, with salivation, pain and difficulty in swallowing. Vomiting of mucus mixed with blood. Tenesmus, diarrhoea, the motions containing blood and mucus. Dysuria, with passage of small amounts of albuminous and bloody urine. Peritonitis, high temperature, quick pulse, headache, loss of sensibility, and convulsions. _Post-Mortem._--Gastro-intestinal mucous membrane inflamed, with gangrenous patches. Genito-urinary tract inflamed. Acute nephritis. _Treatment._--An emetic of apomorphine; demulcent drinks, such as barley-water, white of egg and water, linseed-tea and gruel (but not oils), with a hypodermic injection of morphine to allay pain. _Tests._--The vomited matter often contains shining particles of the powder. The urine will probably be albuminous. XLVI.--ABORTIFACIENTS Emmenagogues are remedies which have the property of exciting the catamenial flow; ecbolics, or abortives, are drugs which excite contraction of the uterus, and are supposed to have the power of expelling its contents. The vegetable substances commonly reputed to be abortives are ergot, savin, aloes (Hierapicra), digitalis, colocynth, pennyroyal, and nutmeg; but _there is no evidence to show that any drug possesses this property_. Lead in some parts of the country is a popular abortifacient. A medicine may be an emmenagogue without being an ecbolic. Permanganate of potassium and binoxide of manganese are valuable remedies for amenorrhoea, but will not produce abortion. The vegetable substances frequently used as abortives are savin and ergot. =Savin= (_Juniperus Sabina_).--Leaves and tops of the plant yield an acrid oil having poisonous properties, and which has even produced death. _Symptoms._--Those of irritant poisons. Purging not always present, but tenesmus and strangury.