. The silver sunbeam : a practical and theoretical text-book on sun drawing and photographic printing. C PHOTOGRAPH CABINET PORTRAITS GAGEs IMPROVED PHOTOGRAPHS. A short time ago, says the British Journal, we mentionedthat we had received a specimen of a new salt, containingsilver, which is sought to be introduced in England as asubstitute for the ordinary nitrate of silver which we havebeen so long accustomed to use. As many were anxiousPI gQ to know the constitu- tion of this salt, wesubmitted a sample toanalysis, and obtainedthe results which weshall now give. Asthe reader is probablyaware,
. The silver sunbeam : a practical and theoretical text-book on sun drawing and photographic printing. C PHOTOGRAPH CABINET PORTRAITS GAGEs IMPROVED PHOTOGRAPHS. A short time ago, says the British Journal, we mentionedthat we had received a specimen of a new salt, containingsilver, which is sought to be introduced in England as asubstitute for the ordinary nitrate of silver which we havebeen so long accustomed to use. As many were anxiousPI gQ to know the constitu- tion of this salt, wesubmitted a sample toanalysis, and obtainedthe results which weshall now give. Asthe reader is probablyaware, the sel clementis sold in small, broken,trans]ucent cakes of aslightly greenish tinge,and which are deliquescent, and therefore, require to beretained in a well-closed bottle. The cause of this tend-ency to deliquesce will be presently shown. The salt isreadily soluble in water without the slightest turbiditybeing produced, and can then be employed for sensitizingpaper, etc., just as in the case of the ordinary silver salt. When submitted to analysis, the sel clement was found tobe composed of—. Nitrate of silver,Nitrate of magnesia,Combined water, 31 5 per 8-5 1000 It will be seen, therefore, that nitrate of silver consti-tutes but little more than one-third of the salt, the nitrateof magnesia and its combined water forming the bulk ofthe sample. In using the nitrate of magnesia it is impos- SEL CLEMENT. 487 sible to avoid the presence of a certain proportion of water,as, when a solution of the nitrate is evaporated to dryness,-and the last portions of water are expelled by heat, thesalt decomposes, and a basic compound is left behind,which yields but little soluble matter to water. Hence, ifthe evaporation be carried so far as to drive off morewater than the proportion shown in the above analysis,the risk would be incurred of producing the insoluble com-pound above referred to. The set clement may be prepared in the following of— Silver, 100 parts. Magn
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