304

Materia Medica.

part II.

1

acetic acid, which only dissolves it. When sulphuric acid isemployed, charcoal, in the proportion of 43 per cent, of theresin acted on, is produced.* The resin of the. Norway sprucepossesses nearly the same properties. It is solid, brittle, intears, of a brownish yellow colour on the outside, and inter-nally white; and emits a very agreeable odour when burning.

Burgundy pitch has a terebinthinate odour and taste, is brit-tle, opaque, and of a light yellow, or reddish-brown colour.It softens moderately in the heat of the hand, appears unctuous,and has a considerable degree of tenacity.

Medical properties and uses. The turpentines and theiressential oil are stimulant, cathartic, diuretic, and anthelmin-tic; and externally rubefacient. Of those which I have de-scribed, the Venice and Canada turpentines are more generallyemployed for internal purposes; the common turpentineproving offensive to most stomachs, and the Chian not beingeasily procured. The ancients were well acquainted with themedicinal properties of turpentines'; and, besides the diseasesfor which they are prescribed by the moderns, gave them libe-rally in coughs and ail pulmonary affections. Turpentinesseem to derive their virtues from the oil they contain. Whenswallowed, they produce a sensation of warmth in the sto-mach, increasing the quickness and force of the pulse; and itthe dose be large, some degree of nausea is excited, with slightvertigo, and soon a copious discharge from the bowels ,• but ifsmall, they act chiefly upon the kidneys. The cathartic ope-ration of large doses of the oil, in particular, seems to coun-teract the determination to the kidneys, which smaller dosesproduce; for in doses of even f3x and f5xij, no other effecton the urinary organs is perceived than the violet smell of theurine. 3 The odour of violets is produced by the oil, evenwhen it is not taken into the stomach, or rubbed upon theskin; for if a quantity of oil of turpentine be poured on a tablein a room, this odour will be perceived in the urine of any onewho remains in the room for half an hour, or even a shortertime. Turpentines are chiefly prescribed in gleet, Jeucorrhcea,mucous obstructions of the urinary passages, and calculous af-fections ; but in the latter cases their stimulant operation onthe kidneys requires that they be given with caution. The oilis regarded as a useful remedy in lumbago, sciatica, and someother varieties of chronic rheumatism, particularly when com-bined with the cinch on a bark; and it has lately been verysuccessfully given in unusually large doses for the expulsion

1 Hatchett, Phil. Trans. 1806. * Dioscor. lib. i. cap. 91. p. 50.

i Transactions of the London Medical Society, i. part l. 31S. 2»7.