1821.] Dr. Ure on his Alkalimeter. 15 



ide of iron corresponding to those which have been examined 

 with the other bases. It is not oxidated prussian blue, the blue 

 colour of which is restored by reducing ; but the sulphuric and 

 muriatic acids restore it. Potash decomposes it, leaving a yel- 

 lowish-green mass undissolved. This green powder gives much 

 carbonate of ammonia and empyreumatic oil during decompo- 

 sition. 



Article III. 



On an Alkalimeter and Acidimeter. By Dr. Ure. 

 (To the Editor of the Annals of Philosophy.) 



SIR . Glasgow, April 15, 1821. 



In page 13 of the Introduction to the Dictionary of Chemistry 

 lately published, I have alluded to Dr. Henry in terms which 

 have occasioned a private correspondence between that gentle- 

 man and me, the result of which we are desirous of makino- 

 public in your journal. 



In the beginning of August, 1816, I transmitted to him an 

 Essay on Alkalimetry and Acidimetry, accompanied by a letter, 

 in which I begged him to favour me with his opinion of its merits' 

 cautioning him meanwhile not to communicate its contents to 

 any person. In the eighth edition of his Elements, which 

 appeared in 1818, he published a plan of alkalimetry and acidi- 

 metry modified from that described in my Essay. This struck 

 me at the time as an unwarranted use of my communication - 

 and declining to correspond with him on tbe subject, I resolved' 

 to seize the first favourable opportunity to reclaim my rights. 

 Under this feeling I wrote the paragraph in the Introduction to 

 the Dictionary. 



Dr. Henry thus writes me on the 12th of April, 1821, "I 

 assure you that I had not at the time of publishing my book, 

 nor can I now recall, the remembrance of any injunction of 

 secrecy, respecting your alkalimeter. I conceived I had so 

 expressed myself, at p. 512, vol.ii. of my Elements, as unequi- 

 vocally to give to you the credit of inventing an instrument on 

 the principle of directly, and without calculation, indicating the 

 per centage of alkali in any specimen ; and that I pretend to 

 nothing more than the modification of your method which is 

 described in my book."* 



Under these circumstances, I am satisfied that Dr. Henry had 



• " It lias been very properly objected to it (tbe alkalimeter of Descroisilles) by Dr. 

 Ure, of Glasgow (in an Essay on Alkalimetry, which he was so good, about two years 

 ago, as to communicate to me in manuscript, and which, I believe, he has not yet pub- 

 lished), that these degrees, being entirely arbitrary, do not denote the value of alkalies in 

 language universally intelligible; and he lifts proposed an instrument which shall at 

 once, and without calculation, declare the true proportion of alkali in I0 f > parts of any 

 specimen. The principal deviation in the following rules from the method uf Dr. Ure, 

 w, &c. &c— (Henrys Elements sfthemlstey, vol. ii. p. b\.) 



