According to Dr. Sansom carbolic acid is readily taken up by air, so that 159.44 cubic inches of air, at 60° Fah., contain one grain of carbolic acid. Air thus _carbolised_ (currents excluded) entirely annuls putrefaction and fungoid manifestation on the surface of putrescible fluids, and such carbolised air is more permanently efficacious than air charged with the fumes of chloride of lime or sulphurous acid, and it may be breathed with impunity by mammifers.
These few observations will, I think, satisfy your readers that Mr. Sutton’s remarks are erroneous and without foundation. I shall be glad to learn that photographers have tried carbolic acid in the preservative solution for dry plates, and would recommend them to make a solution of carbolic acid, one part to one thousand parts of water, and then add their albumen to this solution to the strength they require it. Above all things it is essential that the carbolic acid be of good quality for photographic purposes; and I would recommend them to use an acid such as Calvert’s No. 1 (gilt label) carbolic acid.—I am, yours, &c.,
_Bradford, near Manchester, January 27, 1872._
GENTLEMEN,—It is over two years since I devised the carbolic mixture for detecting traces of albumen. At the time I did not think it of sufficient photographic interest to occupy your space in detailing experiments on the subject; but, as you do not remember the author’s name, I beg to remind you that I am the author. It was published, I believe, as a note by a friend of mine—an eminent chemist and toxicologist—in a medical work.
On one occasion we were talking over the means of detecting albumen, and having experimented with phenol or “carbolic acid” for about eight years, many times in connection with albumen, I knew its properties well, and, on my attention being directed to a test for albumen, I commenced experiments with a mixture of phenol and acetic acid, then with the addition of alcohol, and finally with phenol and alcohol, equal parts by weight. My friend and self then went through a comparative set of experiments side by side—my friend taking his old nitric acid test and I my new phenol mixture—the result being that my test indicated albumen both in plain water and urine, diluted one in ten after the nitric acid failed to indicate any further.—I am, yours, &c.,