3. Now polish with an old white silk handkerchief. If this latter precaution be not taken, small particles of linen will be left upon the plate: these are perhaps only seen when draining off the collodion; they form nuclei and eddies, checking the collodion in its course. Some of these minute fibers are washed off, and contaminate the next picture. To all lovers of clean pictures our advice therefore is, having well dried the plate with old linen, lay it, clean side upwards, upon a few sheets of common glazed demy paper (not blotting), and rub it hard with the silk until sensibly warm; this has the double advantage of dispersing fibers and moisture, for all glass plates are slightly in a hygrometric condition. Double the silk rubber up to form a pad, and with this the glass must be firmly dusted down just before pouring on the collodion, which will then run most evenly; if the coated plate is now viewed by transmitted light, not a speck or blemish will be seen upon it. When a plate cleaned as above described is breathed upon, the moisture does not evaporate slowly, but _flies off_. Do not be afraid of putting the glass into an electrical condition with the silk rubber; on this account objections have been raised to the use of silk; practically, however, I find it a most valuable auxiliary in this starting-point of the process, the perfect manipulation of which makes an important difference in the value of the finished picture. What can be more inartistic and annoying to an educated eye than spots, patches, stars, and sky-rockets, the forms and shapes of which rival, in numberless variety, a display of fireworks? Let us not, therefore, be contented with pictures, however good in other respects, presenting these deformities--so many blots on the photographic escutcheon. _To clean a glass after having used it, when not varnished._--Wash off the collodion film with water, then clean the marked side with plain tripoli and water, and dry as above. _To coat the plate._--First remove all the particles of dried collodion from the mouth of the bottle. Now pour upon the center of the cleaned glass as much collodion as it will hold. Do not perform this operation hurriedly, take time, and systematically incline the plate in such a manner that the collodion may run into each corner in succession; when perfectly covered, pour off gently the excess into the bottle at one of the corners nearest to you; with observation and practice dexterity is easily acquired. There are many ways of coating the plate; each person will adopt that which practice teaches him is best. The pneumatic plate-holder is a convenient little instrument to use for holding the plate whilst pouring on the collodion; it may be used for both small and large plates. Keep the corner of the glass plate in contact with the neck of the bottle whilst pouring off the collodion; otherwise the film will be wavy in places.