440 Proceedings of the British Association. 



beneficial or injurious properties as it contained the iron in the higher 

 or lower degree of oxidation. 



1 On the Energiatype and the Property of Sulphate of Iron in deve- 

 loping Photographic Images,' by Mr. R. Hunt. — In a former number of 

 the Athenceum [ante, p. 500] the author communicated the discovery of 

 a new photographic process of great sensibility, to which the above 

 name was given. It consisted essentially in the development of a dor- 

 mant photographic image, formed on a paper prepared with succinic 

 acid and nitrate of silver, by the deoxidizing power of sulphate of iron. 

 Numerous failures had been communicated to the author, which ap- 

 peared to arise from the varying rates of solubility possessed by suc- 

 cinic acid obtained from different manufacturers. It was now recom- 

 mended, that five grains of succinic acid should be put into a fluid 

 ounce of distilled water, and allowed entirely to dissolve — the salt and 

 gum is then to be added to this solution, and the author believes that, 

 with care, the effects will be certain. Recent researches have, how- 

 ever, proved that this property of the sulphate of iron may be made 

 available on any photographic paper. On paper merely washed with the 

 nitrate of silver, good camera pictures have been thus obtained in a 

 few minutes, and on papers prepared with the chloride of sodium, 

 bromide of potassium, particularly the iodide of potassium, camera 

 views are procured in less than a minute. Mr. Hunt exhibited a great 

 number of specimens procured on the above and many other salts of 

 silver — the most beautiful being procured on papers covered with the 

 acetate, the benzoate, the citrate, and other organic salts of silver. 

 These drawings were all fixed by washing with moderately strong am- 

 monia. 



Prof. Grove called the attention of the Section to a new photogra- 

 phic process, by which pictures might be obtained by one operation. 

 Papers were prepared with the iodide of potassium, nitrate of silver, 

 and gallic acid, in the same manner as for Mr. Fox Talbot's calotype 

 process, and then allowed to darken. The paper is again washed over 

 with the iodide of potassium in solution, and dried. When required 

 for use, it is to be immersed in a weak solution of nitric acid in water, 

 and then exposed to light. In a very few minutes, copies of engravings 

 could be procured. 



1 On Guano,' by Mr. Warrington. — This was a notice, intended particu- 

 larly to draw attention to the imperfect manner in which the estimation 

 of the nitrogen in the analysis of guano, was given to the agriculturist. 

 On the quantites of nitrogen depended, in a great degree, the value of 

 a given sample, whereas in general the quantity of ammoniacal salts was 



