PHARMACEUTICAL PREPARATIONS 675 



use act speedily, but their effects are less powerful and per- 

 manent than those of the ointments. Though producing 

 considerable irritation, they seldom cause blistering, unless 

 applied repeatedly at short intervals. In using them, it 

 is not essential that the hair be removed, nor even that the 

 animal be kept idle. They may be applied repeatedly to 

 the same spot without fear of blemishing. 



Vinegar of cantharides made with one part of powdered 

 flies and ten of acetic acid forms a prompt counter-irritant. 

 The B.P. Acetum Cantharidis is prepared with two parts 

 cantharides, and 10 parts each of glacial acetic acid and 

 water. 



Ointments of cantharides are much used. Their olea- 

 ginous constituents ensure solution of the cantharidin, and 

 render them easy of application. Many contain a number 

 of ingredients, but the simplest are usually the best. A 

 useful ointment of medium strength consists of one part of 

 powdered cantharides to six of benzoated lard, palm oil, 

 or vaseline. A stronger ointment is made with one ounce 

 each of mercury bmiodide and cantharides, and eight 

 ounces of vaseline or benzoated lard. Such an ointment, 

 when well made and applied with smart friction, acts 

 effectually. Another excellent ointment is made with one 

 part each of powdered cantharides, Venice turpentine, and 

 resin, with four parts of vaseline, palm oil, or lard. The 

 powdered flies are digested with the oily matters in a 

 covered vessel, over a slow fire or a water-bath, for twelve 

 hours, and the vessel placed in boiling water for fifteen 

 minutes ; any wax or resinous matters used to give con- 

 sistence are then melted and stirred in, any volatile flavour- 

 ing oil added, and the mixture, if required, strained through 

 muslin. 



French, German, and Belgian practitioners frequently, 

 however, add other irritants to their cantharides blisters. 

 Degive states that numerous experiments convince him 

 that the best vesicant is made of ten to fifteen parts each 

 of cantharides and corrosive sublimate dissolved in one 

 hundred parts of vaseline. The part is prepared by clipping 

 the hair, and washing with soap and water. The ointment 

 is rubbed in for ten minutes, and, if needful, six hours later 



