तस्यापिहितकाचकस्योदके निमज्जत एकदेशः सीदति पटलान्तरेषु वा सूच्या भिद्यते ॥ ॥
tasyāpihitakācakasya udake nimajjata ekadeśaḥ sīdati paṭalāntareṣu vā sūcyā bhidyate
ガラスの覆いで封じたそれについては、水に沈めると一部が沈む。あるいは層の間を針で刺して(試験する)。
They are quick, low-cost, and reproducible—ideal for routine enforcement by inspectors without specialized equipment.