MERCURY OINTMENT 289 



and one ounce of suet. Trituration is continued until 

 metallic globules cease to be visible. A good ointment con- 

 tains about one per cent, of its mercury in a state of oxide, 

 and infriction and exposure during application increase this 

 more active oxidised portion, which is dissolved by the salts 

 and fatty acids of the skin. This strong ointment is usually 

 diluted with two or three parts of hog's lard or soft soap ; or 

 used in the form of unguentum hydrargyri compositum, 

 which contains ten parts mercury ointment, six parts each 

 of yellow wax and olive oil, and three parts of camphor. 



ACTIONS AND USES. Mercurial ointment, when merely laid 

 on the surface of the skin, exerts slight topical effect, and is 

 only very gradually absorbed. When applied with smart 

 friction it is more quickly absorbed, and, in considerable 

 amount, irritates, vesicates, and induces constitutional 

 effects. Two ounces of the strong ointment, rubbed daily 

 into the skin of a horse, salivates in four or five days : but 

 according to Bouley, three ounces may, without fatal 

 effects, be thus applied daily for a week. Lafosse produced, 

 however, grave constitutional effects in cattle by rubbing 

 three ounces into the throat (Kaufmann). 



Mild dressings encourage the healing of indolent ulcers, 

 and promote a healthier action in psoriasis and other per- 

 sistent scaly skin disorders. For the successful treatment 

 of psoriasis and allied complaints, Williams recommended 

 the internal as well as the external use of liquor arsenii et 

 hydrargyri iodidi. Although not superior to many safer 

 remedies, it is sometimes used for destroying ringworm fungi, 

 and killing lice, the acari of mange and scab, and other skin 

 parasites, and for such purposes is frequently conjoined with 

 tar oils, sulphur, or iodine. As a counter-irritant and 

 absorbent the strong ointment is employed in reducing 

 swelling of joints and tendons. 



Mercurial ointment is apt, however, to be used too freely 

 and indiscriminately. When incautiously used it not only 

 causes undue irritation, but is apt to produce poisoning 

 after being absorbed. Many cattle and sheep, dressed for 

 skin complaints and skin parasites, suffer from mercurial 

 poisoning, and some of these cases terminate fatally. In 

 Lincolnshire a lot of scabby sheep were treated with blue 



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