"I have now made the preparation; laid as it were the foundations of my answer to the Sieur Burn's [or Brun's] demand; namely, that having put two pounds six ounces of fine English tin into an iron vessel, and heated it strongly on an open fire for six hours, stirring it continually, without having added anything, he obtained two pounds thirteen ounces of a white ; which at first occasioned him great surprise, and the desire to ascertain whence these seven ounces of increase were derived."