SCIENCE. 



181 



tially decomposed by oxalic acid till the color is reduced to 

 a bluish-black tinge. 



Application. — A suitable quantity of the re-agent, pre- 

 pared as above, is added to a solution of free ammonia or 

 its carbonate, in the same way that Nessler's solution of 

 mercuric per-iodide is used in Manklyn's well-known pro- 

 cess. 



Result. — The combination of the ammonia with part or 

 all of the oxalic acid of the colorless ferric oxalate of the 

 re-agent, and the blackening of the solution by the re-form- 

 ation of ferric gallate. 



Estimation of Ammonia. — By an imitation of a standard 

 solution of ammonia with the re-agent, as in Wanklyn's 

 mode of Nesslerizing. When the solution to be tested 

 and the imitation solution correspond in color, it is 

 inferred that they contain equal quantities of ammonia. 

 In this process the standard ammonia test should be made 

 from the carbonate, and its strength may be such that one 

 litre shall contain one milligramme of ammonia, or one 

 part in a million. Another and more direct way of esti- 

 mating ammonia is by adding a standard test solution of 

 oxalic acid to the blackened solution of the re-agent and 

 liquid to be tested, till the original color is produced, and 

 from the known quantity of oxalic acid used to calculate 

 the quantity of ammonia in the resulting oxalate. Chem- 

 ists will find this re-agent both convenient and sensitive. 



THE UNITY OF NATURE. 

 By the Duke of Argyll. 



In the preface to the first edition of the " Reign of Law," 

 published in 1866, the following passage occurs : — " I had 

 intended to conclude with a chapter on Law in Christian 

 Theology. It was natural to reserve for that chapter all 

 direct reference to some of the most fundamental facts of 

 Human Nature. Yet, without such reference, the ' Reign 

 of Law,' especially in the ' Realm of Mind,' cannot even 

 be approached in some of its very highest and most impor- 

 tant aspects. For the present, however, I have shrunk 

 from entering upon questions so profound, and of such 

 critical import, and so inseparably connected with religious 

 controversy." 



The great subject spoken of in this passage has ever 

 since been present with me. Time, indeed, has only in- 

 creased my sense of its importance. But the years have 

 also added, perhaps in more than equal proportion, to my 

 sense of its depth and of its difficulty. What has to be 

 done, in the first place, is to establish some method of in- 

 quiry, and to find some secure avenue of approach. Before 

 dealing with any part of the Theology which is peculiarly 

 Christian, we must trace the connection between the Reign 

 of Law and the ideas which are fundamental to all religions. 

 It is to this preliminary work that the following chapters 

 have been devoted. Modern Doubt has called in question 

 not only the whole subject of inquiry, but the whole fac- 

 ulties by which it can be pursued. Until these have been 

 tested and examined by some standard which is elemen- 

 tary and acknowledged, we cannot even begin the work. 



It has appeared to me that not a few of the problems 

 which lie deepest in that inquiry, and which perplex us 

 most, are soluble in the light of the Unity of Nature. Or 

 if these problems are not entirely soluble in this light, at 

 least they are broken up by it, and are reduced to fewer and 

 simpler elements. The following chapters are an attempt 

 to follow this conception along a few of the innumerable 

 paths which it opens up, and which radiate from it through 

 all the phenomena of the Universe, as from an exhaust- 

 less centre of energy and of suggestion. 



It is the great advantage of these paths that they are al- 

 most infinite in number and equally various in direction, 

 To those who walk in them nothing can ever come amiss. 

 Every subject of interest, every object of wonder, every 

 thought of mystery, every obscure analogy, every strange 

 intimation of likeness in the midst of difference — the whole 

 external and the whole internal world — is the province and 

 the property of him who seeks to see and to understand the 

 Unity of Nature. It is a thought which maybe pursued 

 in every calling — in the busiest hours of an active life, and 

 in the calmest moments of rest and of reflection. And if, 

 in the wanderings of our own spirit and in the sins and 



sorrows of Human Life, there are terrible facts which resist 

 all classification and all analysis, it will be a good result of 

 our endeavors to comprehend the Unity of Nature, should 

 it lead us better to see, and more definitely to understand, 

 that which constitutes The Great Exception. 



I commend these chapters to the consideration, and I 

 submit them to the criticism, of those who care for such 

 inquiries. Like the former Work, of which this is a se- 

 quel, some parts of it have appeared separately in another 

 form. These have been reconsidered, and to some extent 

 re-written ; whilst a new meaning has been given to the 

 reasoning they contain by the place assigned to them in a 

 connected treatise. 



The publication of it as a series of Articles, before its 

 final appearance as a volume, will afford me, I hope, 

 the advantage of hearing and of seeing what may be 

 said and written of its errors or of its deficiencies. Per- 

 haps, also, it may afford me an opportunity, before the 

 whole of these Articles have appeared, of writing at least 

 one more chapter on an important subject, for which leis- 

 ure fails me now. 



GENERAL DEFINITIONS AND ILLUSTRATIONS OF THE UNITY OF 

 NATURE — WHAT IT IS, AND WHAT IT IS NOT. 



The system of Nature in which we live impresses itself 

 on the mind as one system. It is under this impression 

 that we speak of it as the Universe. It was under the same 

 impression, but with a conception specially vivid of its 

 order and its beauty, that the Greeks called it the Kosmos. 

 By such words as these, we mean that Nature is one whole 

 — a whole of which all the parts are inseparably united — 

 joined together by the most curious and intimate relations, 

 which it is the highest work of observation to trace, and of 

 reason to understand. y 



I do not suppose that there is any need of proving this — 

 of proving, I mean, that this is the general impression which 

 Nature makes upon us. It may be well, however, to trace 

 this impression to its source — to see how far it is founded 

 on definite facts, and how far it is strengthened by such 

 new discoveries as science has lately added to the knowl- 

 edge of mankind. 



One thing is certain : that whatever science may have 

 done, or may be doing, to confirm man's idea of the unity 

 of Nature, science, in the modern acceptation of the term, 

 did not give rise to it. The idea had arisen long before sci- 

 ence in this sense was born. That is to say, the idea existed 

 before the acquisition of physical knowledge had been 

 raised to the dignity of a pursuit, and before the method 

 and the results of that pursuit had been reduced to sys- 

 tem. Theology, no doubt, had more to do with it. The 

 idea of the unity of Nature must be at least as old as the 

 idea of one God ; and even those who believe in the deriva- 

 tion of Man from the savage and the brute, cannot tell us 

 how soon the Manotheistic doctrine arose. The Jewish 

 literature and traditions, which are at least among the old- 

 est in the world, exhibit this doctrine of the purest form, 

 and represent it as the doctrine of primeval times. 

 The earliest indications of religious thought among the 

 Aryan races point in the same direction. The records of 

 that mysterious civilization which had been established on 

 the Nile at a date long anterior to the call of Abraham, are 

 more and more clearly yielding results in harmony with the 

 tradition of the Jews. The Polytheism of Egypt is being 

 traced and tracked through the ready paths which led to 

 the fashioning of many Gods out of the attributes of One. 1 

 Probably those who do not accept this conclusion as his- 

 torically proved may hold rather that the idea of the unity 

 of Nature preceded the idea of the unity of God, and that 

 Monotheism is but the form in which that earlier idea be- 

 came embodied. It matters not, so far as my present pur- 

 pose is concerned, which of these two has been the real or- 

 der of events. If the law prevailing in the infancy of our 

 race has been at all like the law prevailing in the infancy of 

 the individual, then Man's first beliefs were derived from 

 authority, and not from either reasoning or observation. I 

 do not myself believe that in the morning of the world The- 



1 Renouf, " Hibbert Lectures," 1879. p. 89. 



