As if all these problems were not bad enough, the internal organization of the medical department of the army was so chaotic that, even if adequate supplies were available and if the almost insurmountable problems of communications and transportation were solved, it is almost certain that shortages would have developed at least during the campaign of 1776. Add to this the fact that any retreating army is subject to loss of supplies and the reasons for the shortages become very obvious. The encouragement which Congress, through its Secret Committee, gave to private shippers for the importation of vital war materials offered little relief in the field of medical supplies. Importation was, of course, cut off from England, and France did not directly export any quantity of medical supplies, at least until 1778. American privateers found it much more profitable to prey on British shipping than initiating trade channels with countries which prior to the Revolution were prohibited from shipping directly to the Colonies. These channels of commerce did not develop extensively until well after the Revolution. Hence the most immediate relief from medical supply shortages was provided by the American privateers. Drug cargoes from British prize ships, many of which were en route to New York, served as a most important source of supply, particularly in 1777 and 1778. However, even with the most adequate supplies, competition between different branches of the army and navy and the confiscation of supplies destined for Continental troops by state militias further encouraged inflationary trends. The number of individual drugs mentioned in various inventories was considerable, as evidenced by the listing on page 130. However, of these, only about a dozen constituted the really critical shortages. Heading the list of these "capital articles" was Peruvian or Jesuits' bark, the same cinchona from which quinine was later discovered. Tons of bark were used during the Revolutionary War, and the price more than quandrupled between June 1776 and September 1777. The most prominent group of drugs on the list of capital articles consisted of cathartics and purgatives. Jalap, ipecac, and rhubarb were the botanical favorites, while bitter purging salts (Epsom salts) and Glauber's purging salts were the chemical choices for purging. Tartar emetic (antimony and potassium tartrate) was the choice for a vomit, and cantharides (Spanish flies) was the most important ingredient of blistering plasters. Gum opium was administered for its narcotic effects, while gum camphor, nitre (saltpetre or potassium nitrate), and mercury (pure metal as well as certain salts) were employed for a variety of purposes. Lint, a form of absorbent material made by scraping or picking apart old woven material, also often was short in supply.