316 Profs. J. T. Cash and W. K. Dunstan. [Mar. 5, 



was furnished by analysis. The nitrites which we have prepared are 

 those of methyl, ethyl, primary propyl, secondary propyl, primary 

 butyl, secondary butyl, tertiary butyl, isobutyl, -amyl, /9-amyl, and 

 tertiary amyl. Certain- of these nitrites were prepared by us for the 

 first time, while of those which had already been described some have 

 been found to. possess different physical properties to those usually 

 ascribed to them. For the purposes of administration, a known volume 

 of each nitrite was taken. The relative density of each substance 

 having been previously determined, the weight corresponding to the 

 volume taken was readily calculated, and from this was ascertained 

 the amount of the active nitrite group (N0 3 ) present. 



The apparatus for recording alterations in blood pressure consisted 

 of a mercurial manometer writing upon a slowly rotating drum, and 

 a Pick's kymograph writing upon a more rapidly revolving Balzac's 

 cylinder. These manometers could be employed together or sepa- 

 rately, but, as a rule, when pressure and number of pulsations only 

 were being observed, both were kept open. The advantage of the 

 arrangement is that a considerable period of time is represented by a 

 short lineal movement on a small drum, whilst on the quick one the 

 pulse can be reckoned and the course of the rapidly occurring varia- 

 tions of pressure studied. Respiration was recorded on a registering 

 Marey's tauibour attached to a double tambour placed on the thorax 

 of the animal. An electrical signal, in connexion with a key and 

 Darnell's cell, was placed beneath the point recording the blood 

 pressure in order to mark the time of administration of nitrite. In 

 cases where vagus, splanchnic, -or sciatic stimulation was employed, a 

 double key -admitted the faradic current from the secondary coil of 

 a du Bois- Raymond's indactorium-to the electrodes on which the 

 nerve rested, while at the same time it closed the signal circuit indi- 

 cating the length of stimulation. 



The following represents the course of the nitrite administration. 

 The blood pressure being steady, the clockwork of the quick drum 

 was started so as to bring it up to full speed before the cylinder 

 was made -to rotate by sere-wing up the friction wheel. The nitrite 

 was then introduced into the side tube of the inhaler ; an arrange- 

 ment of valves permitted inspiration only to take place through this 

 tube. The cylinder was started, ariti after a sufficient record of the 

 pulse and respiration for the time being had been recorded, the 

 nitrite was administered, the time of administration being recorded. 

 A sufficient time having elapsed for inhalation, the air-tube of the 

 inhaler was opened, the quick drum being permitted to run as long 

 .as was necessary for the purpose of recording the changes in pulse 

 and pressure. During- the recovery of pressure an occasional record 

 of pulse and respiration was taken on the quick drum, corresponding 

 marks being made on the slowly revolving cylinder. 



