Hay fever : its causes, treatment, and effective prevention : experimental researches / by Chas. Harrison Blackley.

Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: Hay fever : its causes, treatment, and effective prevention : experimental researches / by Chas. Harrison Blackley. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    297/324 (page 259)
    § 409. The plan now pursued was to attach to an aspirator that contained a given quantity of water, a metal plate with a circular opening of four millimetres in diameter in it. The aspirator was now allowed to empty itself, and the time taken in doing so was carefully noted. The instrument was again filled with water, and one of the silver cases with its o » ... intercepting sieve in situ, was put into the position previ- ously occupied by the metal plate. The aspirator was then again allowed to empty itself. In the first experiment the air passed into the instrument through the opening in the metal plate; but in the second it passed through the inter- cepting sieve, and the density and thickness of this latter was regulated so as to make the time occupied by each operation exactly the same. § 410. The next and the most important step of all was to test the apparatus, and to see how far it answered the main object—the interception of the pollen. To accomplish this the following plan was adopted. A given weight of pollen (l-100th of a grain) was distributed in the atmosphere of a room that had 1,000,000 cubic inches of space in it. Whilst the pollen was still floating, one of the silver cases was attached by an india-rubber tube to the instrument shown at Plates II. and III. By inhaling through this it was at once seen to what extent it was pollen-proof in a given number of inspirations. By these means the relation that exists between the freedom of respiration and the power of intercepting pollen could be determined and regulated with the greatest delicacy ; but it was found that it was not possible to secure perfect freedom of breathing and complete interception of the pollen at one and the same time. There was also this curious circumstance in connection with these trials, namely, that in the first few inhalations, all the pollen was retained, whilst the later ones allowed some to pass, and a very strong inspiration would drive a larger number through. I determined, however, to try the method during an entire hay-season, securing the intercep- tion of as much pollen as was possible with a moderate freedom of respiration. § 411. Some imperfect trials were made in 1877, but it 17—2