70 



NOTES AND QUERIES. 



[No. 168. 



would be excellent evidence, were it not for the dark 

 and ambiguous manner in which it is produced. I 

 should have been glad that Mr, Speght had himself 

 seen the record, instead of Master Buckley, of whom I 

 suppose no one knows who he is : why did he not ? 

 I should have been better satisfied if the authority had 

 not been introduced with so hesitating and questionable 

 a phrase as ' not many yeeres since ;' and I also think 

 that it would have been better if Master Buckley had 

 given us the date annexed to the record ; as we should 

 then at least have had the satisfaction of knowing 

 whether it did not belong to some period before our 

 author was born, or after he had been committed to the 

 grave. Much stress, therefore, cannot be laid upon the 

 supposition of Chaucer having belonged to the Society 

 of the Inner Temple." 



Ttbo. 

 ■ Dublin. 



PHOTOGRAPHIC NOTES AND QUEEIES. 



Pyrogallic Acid (Vol. vi., p. 612.). — In answer 

 to the Query of your correspondent E. S., I beg 

 to give the following method of preparing pyro- 

 gallic acid (first published by Dr. Stenhouse), 

 which I have tried and found perfectly successful. 



Make a strong aqueous infusion of powdered 

 galls ; pour it off from the undissolved residue, and 

 carefully evaporate to dryness by a gentle heat : 

 towards the conclusion of the process the extract 

 is very liable to burn ; this is best prevented by 

 continued stirring Avith a glass or porcelain spatula, 

 l^ext, procure a flat-bottomed iron pan, about ten 

 inches diameter and five inches deep. Make a 

 hat of cartridge paper pasted together, about 

 seven inches high, to slip over and accurately fit 

 the top of the iron pan. Strew the bottom of the 

 pan with the gall extract to the depth of three- 

 quarters of an inch ; over the top stretch and tie 

 a piece of bibulous paper pierced with numerous 

 pin-holes ; over this place the hat, and tie it also 

 tightly round the top of the pan. 



The whole apparatus is now to be placed in a 

 sand-bath, and heat cautiously applied. It is con- 

 venient to place a glass thermometer in the sand- 

 bath as near the iron pan as possible. The heat is 

 to be continued about an hour, and to be kept as 

 near 420° Fab. as possible ; on no account is it to 

 exceed 450". The vapour of the acid condenses 

 in the hat, and the crystals are prevented from 

 falling back into the pan by the bibulous paper 

 diaphragm. When it is supposed that the whole 

 of the acid is sublimed, the strings are to be un- 

 tied, and the hat and diaphragm cautiously taken 

 off together ; the crystals will be found in con- 

 siderable quantity, and should be removed into a 

 stoppered bottle ; they should be very brilliant 

 and perfectly white ; if there is any yellow tinge, 

 the heat has been too great. 



I believe that close attention to the above 

 details will ensure success to any one who chooses 



to try the process, but at the same time I must 

 remind your correspondents that scarcely any 

 operation in chemistry is perfectly successful the 

 first time of trial. J. G. H. 



Clapham. 



Stereoscopic Pictures with One Camera (Vol. vi., 

 p. 587.). — In reply to the inquiry of Ramus, allow 

 me to say the matter is not difficult. My plan is as 

 follows: — Suppose a piece of still-life to be the 

 subject. Set up the camera at such a distance as 

 will give a picture of the size intended, suppose it 

 sixteen feet from the principal and central object ; 

 by means of a measuring tape or a piece of string, 

 measure the exact distance from the principal 

 object to the front of the camera. Take and com- 

 plete the first picture ; if it prove successful, re- 

 move the camera about two feet either to the right 

 or left of its first station {i.e. according to the 

 judgment formed as to which will afford the most 

 artistic view of the subject), taking care by help 

 of the tape or string to preserve the same distance 

 between the principal object and the camera, and 

 that the adjustment of focus is not disturbed. In 

 other words, the camera must be moved to an- 

 other part of the arc of a circle, of which the 

 principal object is the centre, and the measured 

 distance the radius. If the arc through which the 

 camera is moved to its second station be too large, 

 the stereoscopic picture will be unnaturally and 

 unpleasingly distorted. The second picture is 

 now to be taken. 



If the subject be a sitter, it is of the utmost 

 importance to proceed as quickly as possible, as 

 the identical position must be retained movelessly 

 till both pictures are completed. This (in my ex- 

 perience) is scarcely practicable with collodion 

 pictures, unless by the aid of an assistant and two 

 levelled developing-stands in the dark closet ; for 

 the time occupied by starting the first picture on 

 its development, and preparing the second glass 

 plate (scarcely less than three or four minutes), 

 will be a heavy tax on the quiescent powers of the 

 sitter. This difficulty is avoided by adopting the 

 Daguerreotype process, as the plates can be pre- 

 pared beforehand, and need not be developed 

 before both pictures are taken. In this case the 

 only delay between the pictures is in the shifting 

 the position of the camera. This is readily done 

 by providing a table of suitable height (instead of 

 the ordinary tripod), on which an arc of a circle is 

 painted, having for its centre the place of the sitter. 

 If the sitter be at the distance of eleven or twelve 

 feet (my usual distance with a 3^ inch Voight- 

 lander), the camera need not be moved more than 

 ten or twelve inches ; and even this distance pro- 

 duces some visible distortion to an accurate ob- 

 seiVer. 



The second levelling stand is required when 

 using the collodion process, because the second 



