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Peas
Shell the peas as soon as taken from the vines, wash and pack into jars, shaking down meanwhile. Set the cans over lukewarm water on the cloth-covered rack or on the bits of wood in the canner, put on the cover, and let stand until the water boils; then fill each jar to overflow with boiling water and cook until the peas are nearly tender; adjust the rubbers, add boiling water, and set the lids in place; let cook ten minutes, then tighten the lids.
This is a boiling-water method for a low-acid vegetable, and that is the whole problem. The instructions are clear and workable as period technique, but the science behind them was not yet understood, and no adjustment of times or jar sizes makes the method sound.
- Why peas cannot be water-bath cannedPeas are low-acid, with a pH well above 4.6. Water-bath processing tops out at 212F, which does not destroy Clostridium botulinum spores; those spores survive, then germinate in the anaerobic, moist, low-acid interior of a sealed jar and produce botulinum toxin. Low-acid vegetables require a pressure canner reaching 240F or above.
- The method here is not even a full boiling-water processThe jars start over lukewarm water and are brought up gradually, the peas are cooked only until "nearly tender," and the final processing after the lids go on is ten minutes. That is a fraction of the exposure a modern pressure process requires, and at the wrong temperature besides.
- Open-kettle style fillingFilling jars to overflow with boiling water and setting the lids in place partway through the heating leaves headspace, vacuum and internal temperature uncontrolled; there is no validated vent-and-process cycle here.
- No measured times, weights or jar sizesThe original gives no jar size, no altitude adjustment and no processing time beyond "ten minutes." Safe low-acid canning depends entirely on those numbers being specified and followed; a recipe without them cannot be corrected by eye.
- Botulinum toxin gives no warningSpoiled peas of this kind may look, smell and taste normal. There is no sensory test that clears a jar, which is why the process itself has to be the safeguard.
- The "cloth-covered rack or bits of wood"The 'cloth-covered rack or bits of wood' -- These are simply improvised standoffs to keep glass jars off the hot bottom of the boiler so they do not crack. A wire canning rack does the same job.
- If you want canned peasUse a current tested process from a pressure-canning guide, or freeze the peas instead. Freezing suits young peas well and needs no processing calculation.
Home canning books of the late nineteenth and early twentieth centuries treat vegetables and fruits as broadly the same problem, and the results were wildly uneven: fruits, jams and pickles genuinely are preserved by their own acidity and sugar, while peas, beans, corn and greens are not. The gradual, gentle heating described here is most straightforwardly explained as a way of avoiding thermal shock to the glass, rather than as a method aimed at reaching a specific lethal temperature. Some writers of the era hedged by recommending the "intermittent" or fractional method, boiling jars on three successive days in the hope of catching spores as they germinated; that too proved unreliable. Pressure retorting was long established in commercial canning, and botulism outbreaks traced to home-canned vegetables in the 1910s and 1920s drove the push to get pressure canners into home use; by the 1930s American extension services were telling households plainly that low-acid vegetables belonged in a pressure canner. Pages like this one survive as a record of the practice that change replaced.