88 report — 1859. 



tungstate of soda alone can be used, because this salt alone allows of passing the iron 

 smoothly over the fabric without injuring it. Tungstate of soda is a cheap salt at 

 present, because it is manufactured for the precipitation of tungstate of lead, which is 

 now in frequent use instead of white lead ; and although a solution of 20 per cent, of 

 tungstate of soda is required, this represents only a small volume of the salt. It has 

 proved very useful, and is now in constant use in Her Majesty's laundry. A solution 

 of it cannot be preserved without adding a small proportion of phosphoric acid, or of 

 phosphate of soda, to prevent the formation of a bitungstate of little solubility. 



Besides the experiments hitherto referred to, others were necessary, in order to 

 ascertain the possibility of permanently fixing antiflammable substances into the fibre 

 so as to prevent them from being removed by water. The following substances were 

 tried without success : — by Morin, tannate of zinc mixed with glue ; by others, sul- 

 phate of lime; by the authors of this communication, sulphate of baryta, the silicates 

 of alkaline earths and of earths, aluminate of zinc, oxychloride of antimony, arseniate 

 of tin, and the stannates of lime and of zinc. It was found possible, however, to fix 

 either of the following substances : — the borate and the phosphate of tin, stannate 

 of tin and hydrated protoxide of tin. But all these substances give a yellowish tinge 

 to the fabrics, and are only applicable to coarse materials, such as canvas and sail- 

 cloth. The protoxide of tin is precipitated from a solution of two parts of protochlo- 

 ride of tin in one part of water by concentrated carbonate of soda. Care must be 

 taken to agitate the fabric in the latter solution, in order not to fix anhydrous prot- 

 oxide, which was found to be formed in all cases where a concentrated solution of 

 protochloride of tin was mixed with an excess of concentrated carbonate of soda. It 

 gets transformed into the hydrate by boiling it with protochloride of tin. A piece of 

 sailcloth prepared with it is undergoing practical tests by command of the Store- 

 keeper-General of the Navy. 



On Combinations of Earthy Phosphates with Alkalies. 

 By Professor Voelcker, Ph.D., F.C.S. 



Account of Experiments on the Equivalent of Bromine. 

 By W. Wallace, Ph.D., F.C.S. 



The author employed the bromide of arsenic, a compound which is readily obtained 

 in a perfectly pure state by distillation and crystallization. The mean number obtained 

 was 79"74, which does not differ materially from the equivalent of Marignac. 



On Proposed Improvements in the Manufacture of Kelp. 

 By W. Wallace, Ph.D., F.C.S. 



Great loss of iodine occurs in the present mode of fabrication, and certain sulphur 

 compounds are produced which are highly objectionable and cause a great waste of 

 oil of vitriol in their neutralization or decomposition. Dr. Wallace described various 

 suggestions by which a much greater quantity of kelp might be prepared in the He- 

 brides, and the quality very much improved. 



Mr. Napier's New Process of Etching Glass in relief by Hydrofluoric Acid. 

 Communicated by Professor G. Wilson. 



This process, devised and patented by Mr. Napier, is exceedingly ingenious, and 

 for many purposes of art highly satisfactory. A wood-cut with a device printed in 

 the usual way in printers' ink, is attached by a paste of starch to the surface of glass 

 intended to be etched, and the whole is allowed to dry. 



The prepared glass is then plunged into dilute hydrofluoric acid, left there for a 

 short time ; then washed and the paper cleaned off. 



During the brief immersion the acid has penetrated the paper, including the starch, 

 wherever the former was free from ink-marks, and has corroded or dissolved away 

 the glass over all the points or spaces corresponding to the white paper ; whilst the 

 ink-lines making up the design have acted like a protective varnish, defending the 

 glass below them from corrosion. 



The peculiarity of the process lies in allowing the paper, as well as the ink, to 



