[HINTS ON THE MANIPULATION OF GLASS AND ON GLASS-BLOWING FOR LABORATORY PURPOSES]
§ 1. THE art of GLASS-BLOWING has the conspicuous advantage, from the point of view of literary presentation, of being to a great extent incommunicable. As in the case of other delightful arts — such as those treated of in the Badminton Library, for instance — the most that can be done by writing is to indicate suitable methods and to point out precautions which experience has shown to be necessary, and which are not always obvious when the art is first approached. It is not the object of this work to deal with the art of GLASS-BLOWING or any other art after the manner befitting a complete treatise, in which every form of practice is rightly included. On the contrary, it is my wish to avoid the presentation of alternative methods.
I consider that the presentation of alternative methods would, for my present purpose, be a positive disadvantage, for it would swell this book to an outrageous size; and to beginners — I speak from experience — too lavish a treatment acts rather by way of obscuring the points to be aimed at than as a means of enlightenment. The student often does not know which particular bit of advice to follow, and obtains the erroneous idea that great art has to be brought to bear to enable him to accomplish what is, after all, most likely a perfectly simple and straightforward operation.
This being understood, it might perhaps be expected that I should describe nothing but the very best methods for obtaining any proposed result. Such, of course, has been my aim, but it is not likely that I have succeeded in every case, or even in the majority of cases, for I have confined myself to giving such directions as I know from my own personal experience will, if properly carried out, lead to the result claimed. In the few cases in which I have to refer to methods of which I have no personal experience, I have endeavoured to give references (usually taking the form of an acknowledgment), so that an idea of their value may be formed. All methods not particularised may be assumed by the reader to have come within my personal experience.
§ 2. Returning to GLASS-BLOWING, we may note that two forms of GLASS-BLOWING are known in the arts, "Pot" blowing and "Table" blowing. In the former case large quantities of fluid "metal" (technical term for melted glass) are assumed to be available, and as this is seldom the case in the laboratory, and as I have not yet felt the want of such a supply, I shall deal only with "table" blowing. Fortunately there is a convenient book on this subject, by Dr. Shenstone (Rivingtons), so that what I have to say will be as brief as possible, consistent with sufficiency for everyday work. As a matter of fact there is not very much to say, for if ever there was an art in which manual dexterity is of the first and last importance, that art is glass-working.
I do not think that a man can become an accomplished glass-blower from book instructions merely — at all events, not without much unnecessary labour, — but he can learn to do a number of simple things which will make an enormous difference to him both as regards the progress of his work and the state of his pocket.
§ 3. The first thing is to select the glass. In general, it will suffice to purchase tubes and rods; in the case where large pieces (such as the bulbs of Geissler pumps) have to be specially prepared by pot-blowing, the student will have to observe precautions to be mentioned later on. There are three kinds of glass most generally employed in laboratories.
obtained for the most part from factories in Thuringia, and generally used in assembling chemical apparatus. — This glass is cheap, and easily obtainable from any large firm of apparatus dealers or chemists. It should on no account be purchased from small druggists, for the following reasons:-
(a) It is usually absurdly dear when obtained in this way.