A. H. Taylor

Sampling devices for determining the bacterial content of air.

Appraisal of air contamination by micro‐organisms which are responsible for infectious diseases or result in spoilage of products requires devices for sampling the air to determine bacterial content. The simplest technique involves the use of open petri dishes containing culture media upon which colonies of the organisms can grow. However, quantitative data require the use of devices which will sample the bacterial content of definite volumes of air.Air samplers which yield quantitative data may be roughly divided into bubbler and impinger types. In the former type a definite quantity of air, with or without atomization, is bubbled through water, thus collecting a large part of the organisms. In the impinger types the organisms are deposited on the culture medium, either by use of high linear velocity of the air or by application of an electrostatic field.The authors have developed two types of impinger samplers. One of these, weighing approximately 12 pounds, employs an electrostatic field of about 7000 ...

Spectral radiation involved in protoreactivation of ultraviolet-irradiated cultures of micro-organisms

Abstract Cultures of E. coli irradiated by ultraviolet energy of λ2537 can be partially reactivated by visible blue light from λ4500 to λ3800. Reactivation becomes most evident in the long-wave ultraviolet in the region of λ3650 or the so-called “black light” band of the mercury spectrum. These results are primarily qualitative. The use of color filters to isolate various bands of tungsten spectra in addition to obtaining monochromatic energy by means of a quartz spectrograph tend to place the region of maximal photoreactivity between λ3500 and λ4500. Simultaneous irradiation of air-borne respiratory micro-organisms with λ2537 ultraviolet and with visible light and near-ultraviolet energy from 4500° K fluorescent tubes showed no significant or measurable reactivation by the latter, even though the illumination was much higher than that generally prevailing indoors.