nty drops of alcohol to an ounce of collodion. The feathery appearance
is difficult to comprehend, without seeing a specimen. If you are using
glass which has been previously used, the most minute remains of iron would
cause a discoloration. Muriatic acid is the most effectual remedy for
cleaning glass so used. It may be procured at_ 21/2d. _per lb., and should be
diluted with three parts of water._

AN AMATEUR (Oxford). _We are not of opinion that Mr. Talbot could restrain
any one from taking collodion portraits, as patentee of the Talbotype
process. It is done in many parts of London daily without any
permission.--See _Times'_ Advertisements, &c._

C. E. F. _We think you use too strong a solution of the ammonio-nitrate of
silver: thirty grains to the ounce of water, and then redissolved with the
strong liq. ammon., give to us most satisfactory result,--the paper being
prepared before with chloride of barium, chloride of sodium, and chloride
of ammonia, of each half a drachm to the quart of water, in which half an
ounce of mannite, or sugar of milk, has been previously dissolved. When
sufficiently printed, put it into the hypo. sulph. solution, without
previous immersion._

H. L. L. _We shall be happy to render you the best assistance we can, if
you will communicate with us again. For iodized paper we may safely refer
you to our advertising columns._

_A few complete sets of_ "NOTES AND QUERIES," Vols. i. _to_ vi., _price
Three Guineas, may now be had; for which early application is desirable._

"NOTES AND QUERIES" _is published at noon on Friday, so that the Country
Booksellers may receive Copies in that night's parcels, and deliver them to
their Subscribers on the Saturday._

* * * * *

NEW ACHROMATIC MICROSCOPES on MR. PRITCHARD'S construction, Micrometers,
Polarizing Apparatus, Object glasses, and Eye-pieces. S. STRAKER supplies
any of the above of the first quality, and will forward by post free a new
priced List of Microscopes and Apparatus.

162. FLEET STREET, LONDON.

* * * * *

PURE NERVOUS or MIND COMPLAINTS.--if the readers of NOTES AND QUERIES, who
suffer from depression of spirits, confusion, headache, blushing,
groundless fears, unfitness for business or society, blood to the head,
failure of memory, delusions, suicidal thoughts, fear of insanity, &c.,
will call on, or correspond with, REV. DR. WILLIS MOSELEY, who, out of
above 2