Bernard D. Bolas opens his handbook with a frank admission: glass-blowing is 'neither very easy nor very difficult.' This pragmatic tone sets the stage for a manual that prioritizes economy of space and clarity over literary flourish. The author, a practicing laboratory worker, writes in a 'somewhat disjointed style' by design, packing each paragraph with actionable guidance. The book is structured as a progressive course, moving from simple tube cutting to complex internal seals and vacuum apparatus. Naomi Bolas's numerous diagrams anchor the text, providing visual reference for each manipulation described.

From Simple Seals to Special Forms

The first two chapters establish a foundation in basic operations: cutting and sealing tubes, making thermometer bulbs, pipettes, and absorption bulbs. Bolas emphasizes the importance of controlling the direction of cracks—a skill he calls 'leading'—and offers specific techniques for joining tubes of dissimilar glass. He also covers the building of 'special forms from solid glass,' a phrase that hints at the improvisational spirit of the laboratory. The instructions are terse but precise, often noting common pitfalls such as the tendency of glass to crack if heated unevenly. A notable detail is his advice on gripping devices for corrosive solutions, showing an awareness of the practical chemist's needs.

Advanced Apparatus and the Logic of Construction

Chapter III moves into internal seals, air-traps, spray arresters, and filter-pumps. Bolas describes condensers—plain, double surface, and spherical—and Soxhlet extraction apparatus. His approach is analytical: he explains not just how to make a vacuum tube or enclosed thermometer, but why certain shapes and joints are necessary. The section on 'spinning' glass reveals a technique for forming symmetrical bulbs by rotating molten glass. Throughout, the author assumes the reader has access to a blowpipe and bench, but he also includes a chapter on extemporised apparatus using oil or other fuels, suggesting that resourcefulness is as valued as formal training.

Grinding, Drilling, and the Art of the Stopper

Chapter IV covers cold-working techniques: drilling, grinding, and shaping glass without fusion. Bolas provides detailed instructions for grinding stoppers, warning that a mismatch in taper angles cannot be corrected by prolonged grinding—a practical insight born of experience. He recommends copper or type-metal cones for preliminary shaping and stresses the need for frequent lifting to refresh abrasive. The chapter also addresses marking glass, calibrating apparatus, and joining glass to metal. A brief note on grinding lenses is included, though Bolas concedes it is 'scarcely within the scope' of the book. The final chapter summarizes conditions for successful glass-blowing, reinforcing the manual's emphasis on methodical practice.

Bolas's handbook is best read with a blowpipe in hand. The instructions are dense and assume the reader will attempt each operation immediately. Beginners should start with the simplest seals and progress slowly; the author's warnings about cracking and annealing are not to be skipped. The diagrams by Naomi Bolas are essential companions to the text—study them before lighting the flame. This is a working manual, not a theoretical treatise, and its value lies in the patient repetition of its methods.