6l2 PHILOSOPHICAL TRANSACTIONS. [aNNO I78g, 



the composition of nitrous acid seem to be the 2 principles or elements of the 

 atmosphere, viz. phlogisticated and dephlogisticated air. That this is the case, 

 there seems little reason to doubt. Both the composition and decomposition of 

 nitrous acid renders the supposition probable. For, 1 . Nitrous air and dephlo- 

 gisticated air by mixture produce nitrous acid; and nitrous acid, by mere heat, is 

 converted into a mixture of phlogisticated and dephlogisticated airs. 1. Nitrous 

 air, by the methods already related, is changed into phlogisticated air, and these 

 methods seem to consist in abstracting from the nitrous air a quantity of dephlo- 

 gisticated air. 3. When nitrous acid and nitre are produced in a natural way, 

 the process is not well understood ; but the presence of the atmosphere is known 

 to be necessary. 4. Mr. Cavendish's experiment is decisive on this point. The 

 union of the 2 airs in question is effected by means of the electric spark, and 

 nitrous acid is the product. 



In the next place we are to consider, that volatile alkali contains phlogisticated 

 air; for, 1. Volatile alkali, by mere heat, or by the electric spark, is changed 

 into a mixture of phlogisticated and inflammable air; and, 2. The residuum of 

 volatile alkaline air, after the calces of lead have been revived in it, is phlogis- 

 ticated air. Therefore, when volatile alkali, in the form of fume or air, is ap- 

 plied to red-hot manganese, or calcined green vitriol (substances which are then 

 yielding dephlogisticated air,) with these facts in view, it seems not difficult to 

 conceive, that one of the ingredients of the alkali, viz. phlogisticated air, shosld 

 combine with dephlogisticated air, and form nitrous acid or nitrous air. If nitrous 

 acid be formed, it will indeed in that heat, as has been observed, be instantly de- 

 composed; but if the effect of the union be nitrous air, that will sustain the 

 heat without decomposition. How it happens that nitrous air should be formed, 

 and not nitrous acid, or what the reason is, that nitrous air can sustain a red heat 

 without decomposition, when nitrous acid cannot, Mr. M. is unable to say; and 

 it is better to acknowledge our ignorance than advance groundless conjectures. 

 So much may be pronounced as certain, viz. that nitrous air contains less dephlo- 

 gisticated air than nitrous acid ; because it requires the addition of dephlogistica- 

 ted air to become nitrous acid. 



And, lastly, the experiment with the calcined alum proves, that, in*order to 

 produce nitrous air, it is not sufficient merely to apply volatile alkaline air to a 

 substance which is actually yielding dephlogisticated air. Perhaps the presence 

 of another substance is required, which has a strong attraction for phlogiston. 

 Perhaps, in the experiments with the calces of manganese and of iron, the in- 

 flammable principle of the volatile alkali combines with the calces of the metals, 

 and the phlogisticated air, the other component part unites with the dephlogis- 

 ticated air; and if so, it seems not improbable to suppose, that when alum is 

 made use of, the inflammable principle of the volatile aikali having little or no 



