1891.] The Physiological Action of the Paraffinic Nitrites. 315 



mine in what manner this action is conditioned by the different 

 chemical constitution of the various nitrites employed. Since the 

 chemical constitution of these compounds is well established, and 

 their molecules are comparatively simple in structure, and, moreover, 

 as their principal physiological effects are capable of accurate quanti- 

 tative study, it seemed likely that the inquiry would furnish valuable 

 pharmacological results. 



Our knowledge of the physiological behaviour of the organic 

 nitrites has been almost wholly derived from the study of amyl 

 nitrite, which has been observed to produce a similar but far greater 

 effect than its lower homologue ethyl nitrite, whose action, however, 

 has not hitherto been so closely examined as that of the amyl com- 

 pound. Unfortunately it seems certain that the results which have 

 been obtained with amyl nitrite are to a large extent vitiated by the 

 circumstance that, as a rule, insufficient pains have been taken to 

 procure the nitrite in a chemically pure state, whilst, in addition, the 

 usual mode of administration has been such that it is impossible to 

 determine exactly how much of the compound has actually been 

 inhaled. 



It is believed that both these sources of error have been obviated 

 in the present research. The exact composition of each substance was 

 known, and a special apparatus was devised for ensuring the inhala- 

 tion without loss of a definite amount of nitrite, through the trachea 

 in animals, and through the nostrils in the human subject. 



In this, the first part of the communication, an account is given of 

 the principal work which has already been done on this subject, and 

 this is followed by a brief description of the method by which the 

 litrites have been prepared and their purity ascertained. The 

 physiological actions which have been made the subject of special 

 study are those on blood pressure, pulse, and respiration, whilst the 

 'action on striated muscular fibre has also been fully examined. The 

 present paper deals almost entirely with the action of various nitrites 

 on blood pressure, and with the special apparatus used in studying it. 

 A subsequent paper will have reference to the action of these same 

 nitrites in producing contraction of striated muscle, and will conclude 

 with a discussion of the whole of our results, both in their chemical 

 and physiological aspects. 



The nitrites have been prepared by the reaction of the correspond- 

 ing alcohol, previously purified, with sodium nitrite in bhe presence of 

 dilute acid. This has proved to constitute a satisfactory plan of pre- 

 paring the entire series of nitrites with which we have worked. The 

 liquid nitrites, after having been thoroughly washed and dried, were 

 repeatedly distilled, in some cases under reduced pressure, until a 

 liquid boiling at a constant temperature was obtained. Proof that 

 the liquids thus obtained had the composition of the required nitrites 



