TENSION-EQUALIZER UNIT. 



23 



of 1.5 mm., this tube being fire-polished at both ends. A small hole 

 is cut in the end of a pure-gum finger-cot b, which is then slipped over 

 the glass tube and tied carefully with silk thread. At the other end 

 of the tube a one-hole rubber stopper, c, is attached. The finger-cot 

 is then turned inside out and pulled back on itself in such a way as to 

 be drawn over the rubber stopper, to which it is tied with silk thread. 

 A hole is next made through the rubber stopper, in which a piece of 

 small-bore glass tubing d can be inserted, to which a short piece of 

 rubber tubing is attached. By blowing air from a hand bulb through 

 the rubber tubing, the finger-cot is inflated; the closing of the pinch- 

 cock e serves to keep the air inclosed in the finger-cot. When the 

 appliance is to be used, the deflated nose- 

 pieces are inserted into the nostrils and air 

 is forced into each nosepiece in turn until 

 they are sufficiently inflated to fit into the 

 inequalities of the nostrils. The nosepieces 

 should be tested for tightness by inflating 

 them while they are entirely under water. 

 If any part of the nosepieces leaks, bubbles 

 will rise. The tightness of the fit in the 

 nostril should also be tested by having the 

 subject exhale against pressure. The subject 

 first inhales deeply ; the palm of the hand or 

 a piece of cardboard is then placed against 

 the opening of the three-way valve, and the 

 subject attempts to exhale. If a leak occurs, 

 it is detected by the sound of air escaping 



between the nostril and rubber membrane of the nosepiece. The best 

 test is made by covering the edges of the nostrils with soapsuds and 

 applying pressure. Bubbles appear when there is a leak. The nose- 

 pieces are attached to the three-way valve by a piece of rubber tubing 

 and a tube, to which are attached two metal tubes of approximately 

 6 mm. internal diameter. 



When the nosepieces are used, a tight closure of the mouth is some- 

 times obtained by placing two strips of surgeon's plaster over the 

 mouth, from above the upper lip to below the lower lip. The subject 

 draws in his lips and the surgeon's plaster is placed on them before 

 they relax. This method can be used only when the subject is smooth 

 shaven. 



Mouthpiece. The mouthpiece used, which is of the Denayrouse 1 

 type, will be described in connection with the description of the Zuntz- 

 Geppert apparatus, the method of attachment being shown in the 

 description of the later form of the Benedict respiration apparatus. 2 



FIG. 4. Pneumatic nosepiece. 

 a, glass tube to which is fast- 

 ened a rubber finger-cot, b, 

 which is drawn over a rubber 

 stopper, c. A capillary rubber 

 tube, d, serves for dilating the 

 cot b; the clamp e closest after 

 6 is inflated. 



l Regnard, Recherches experimentales sur les variations pathologiques des combustions respira- 

 toires, Paris, 1879, p. 286. 

 2 See pp. 25, 36, and 54. 



